Iewonrq
Iewonrq
Iewonrq
90,000 gasoline and convenience stores throughout the U.S. showed that price for a gallon of unleaded gas
the average price for a gallon of unleaded gasoline was $3.28 (MSN Auto
website, February 2, 2014). The following data show the price per gallon Francisco.
($) for a sample of 20 gasoline and convenience stores located in San
Francisco Media
3.72
20 74.4
27. ) The results of a search to find the least expensive round-trip flights
to Atlanta and Salt Lake City from 14 major U.S. cities are shown in the
following table. The departure date was June 20, 2012, and the return
date was June 27, 2012
Departure City Cost to Fly to Atlanta Cost to Fly to Salt Lake City
Cincinnati 340.1 570.1
New York 321.6 354.6
Chicago 291.6 465.6
Denver 339.6 219.6
Los Angeles 359.6 311.6
Seattle 384.6 297.6
Detroit 309.6 471.6
Philadelphia 415.6 618.4
Washington, D.C. 293.6 513.6
Miami 249.6 523.2
San Francisco 539.6 381.6
Las Vegas 455.6 159.6
Phoenix 359.6 267.6
Dallas 333.9 458.6
28) The Australian Open is the first of the four Grand Slam professional tennis events
held each year. Victoria Azarenka beat Maria Sharapova to win the 2012 Australian
Open women’s title (Washington Post, January 27, 2012). During the tournament Ms.
Azarenka’s serve speed reached 178 kilometers per hour. A list of the 20 Women’s
Singles serve speed leaders for the 2012 Australian Open is provided below.
29 ) The Los Angeles Times regularly reports the air quality index for A) Compute the range and interquar
various areas of Southern California. A sample of air quality index values
for Pomona provided the following data: 28, 42, 58, 48, 45, 55, 60, 49, and
50 32
29 ) The Los Angeles Times regularly reports the air quality index for
various areas of Southern California. A sample of air quality index values
for Pomona provided the following data: 28, 42, 58, 48, 45, 55, 60, 49, and
50
9.630680142
30.) The following data were used to construct the histograms of the
number of days required to fill orders for Dawson Supply, Inc., and J.C. daison
Clark Distributors
rango
2
Desvicion estandar
0.674948558
dawson clark
11 8
10 10
9 13
10 7
11 10
11 11
10 10
11 7
10 15
10 12
31) The results of Accounting Principals’ latest Workonomix survey indicate the
average American worker spends $1092 on coffee annually (The
Consumerist, January 20, 2012). To determine if there are any differences in
coffee expenditures by age group, samples of 10 consumers were selected
for three age groups (18–34, 35–44, and 45 and Older). The dollar amount
each consumer in the sample spent last year on coffee is provided below.
32) that spend the most on advertising. Consumer-goods company Procter &
Gamble has often topped the list, spending billions of dollars annually
(Advertising Age website, March 12, 2013). Consider the data found in the file
Advertising. It contains annual advertising expenditures for a sample of 20
companies in the automotive sector and 20 companies in the department
store sector.that spend the most on advertising. Consumer-goods company Procter &
Gamble has often topped the list, spending billions of dollars annually
(Advertising Age website, March 12, 2013). Consider the data found in the file
Advertising. It contains annual advertising expenditures for a sample of 20
companies in the automotive sector and 20 companies in the department
store sector.
(Advertising Age website, March 12, 2013). Consider the data found in the file
Advertising. It contains annual advertising expenditures for a sample of 20
companies in the automotive sector and 20 companies in the department
store sector.that spend the most on advertising. Consumer-goods company Procter &
Gamble has often topped the list, spending billions of dollars annually
(Advertising Age website, March 12, 2013). Consider the data found in the file
Advertising. It contains annual advertising expenditures for a sample of 20
companies in the automotive sector and 20 companies in the department
store sector.
media
2011 2012 desviacion est.
74 71
78 70 b. What is the primary difference in performance b
79 75
77 77 al final los 2 años tienen el mismo promedio pero e
75 85
73 80
75 71
77 79
34) The following times were recorded by the quarter-mile and mile runners of a
university track team (times are in minutes).
promedio
Quarter-Mile Mile Times:
0.92 4.52
0.98 4.35
1.04 4.6
0.9 4.7
0.99 4.5
) Use the sample data to estimate the mean
rice for a gallon of unleaded gasoline in San
rancisco.
Desviacion estandar
precio promedio del galón de gasolina sin plomo en San Francisco es mucho más alto que el promedio del país
a) Compute the mean price for a round-trip flight into Atlanta and the
mean price for a round-trip flight into Salt Lake City. Is Atlanta less
expensive to fly into than Salt Lake City? If so, what could explain this
difference?
356.7285714 400.95
b. Compute the range, variance, and standard deviation for the two
samples. What does this information tell you about the prices for flights
into these two cities?
rango varianza
249.6 290 5517.408352
291.6
293.6
309.6
321.6
333.9
339.6
340.1
359.6
359.6
384.6
415.6
455.6
539.6
clark
rango
8
svicion estandar Desviacion estandar
2.584139659
a. Compute the mean, variance, and standard deviation for the each of these three samples.
2011 2012
76 76
2.070196678 5.264435935
mary difference in performance between 2011 and 2012? What improvement, if any, can be seen in the 2012 scores?
tienen el mismo promedio pero en el año 2012 fue menos constante, esto lo vimos graciias a la desviacion estandar
s desvicion estandar
Quarter-Mile Mile Times:
0.056391489 0.129537639
0.966 4.534
coheficiente de varianza
0.058376282 0.028570278
41) A consulting firm submitted a bid for a large research project. The firm’s
management initially felt they had a 50–50 chance of getting the project.
However, the agency to which the bid was submitted subsequently requested
additional information on the bid. Past experience indicates that for 75% of the
successful bids and 40% of the unsuccessful bids the agency requested
additional information.
43). In August 2012, tropical storm Isaac formed in the Caribbean and was
headed
for the Gulf of Mexico. There was an initial probability of .69 that Isaac would
become a hurricane by the time it reached the Gulf of Mexico (National
Hurricane Center website, August 21, 2012).
44.) ParFore created a website to market golf equipment and golf apparel.
Management would like a special pop-up offer to appear for female website
visitors and a different special pop-up offer to appear for male website visitors.
From a sample of past website visitors, ParFore’s management learned that
60% of the visitors are male and 40% are female.
The percentage of adult users of the Internet who use Facebook has
increased over time (Pew Research Internet Project, 2013). Of adult Internet
users age 18–49, 81% use Facebook. Of adult Internet users age 50 and
older, 54% use Facebook. Assume that 52% of adult Internet users are age
18–49.
a. What is the prior probability of the bid being successful (that is, prior to the request for additional information)?
50%
b. What is the conditional probability of a request for additional information given that the bid will ultimately be successful?
c. Compute the posterior probability that the bid will be successful given a request for additional information
(.50)(.75) 0.375
(.50)(.75) (.50)(.40) 0.575 0.65
a. Given that a customer missed one or more monthly payments, compute the posterior probability that the customer will def
M = falta de pago
D1 = el cliente no paga
D2 = el cliente paga
b. The bank would like to recall its card if the probability that a customer
will default is greater than .20. Should the bank recall its card if the
customer misses a monthly payment? Why or why not?
H = evento de que Isaac se convierta en huracán cuando llegue a las costas del Golfo de México
T = evento de que Isaac no se convierta en huracán y se mantenga como tormenta tropical cuando llegue al Golfo de México.
a.) What was the probability that Isaac would not become a hurricane but remain a tropical storm when it reached the Gulf of
P(H) = .69
P(T) = P(H C ) =1- P(H) =1-.69 = .31 0.31
b. Two days later, the National Hurricane Center projected the path of
Isaac would pass directly over Cuba before reaching the Gulf of Mexico.
How did passing over Cuba alter the probability that Isaac would
become a hurricane by the time it reached the Gulf of Mexico? Use the
following probabilities to answer this question. Hurricanes that reach the
Gulf of Mexico have a .08 probability of having passed over Cuba.
Tropical storms that reach the Gulf of Mexico have a .20 probability of
having passed over Cuba.
Isaac would pass directly over Cuba before reaching the Gulf of Mexico.
How did passing over Cuba alter the probability that Isaac would
become a hurricane by the time it reached the Gulf of Mexico? Use the
following probabilities to answer this question. Hurricanes that reach the
Gulf of Mexico have a .08 probability of having passed over Cuba.
Tropical storms that reach the Gulf of Mexico have a .20 probability of
having passed over Cuba.
a.) What is the probability that a current visitor to the website is female?
P(F) = .40.
b.) Suppose 30% of ParFore’s female visitors previously visited the Dillard’s
Department Store website and 10% of ParFore’s male visitors
previously visited the Dillard’s Department Store website. If the current
visitor to ParFore’s website previously visited the Dillard’s website, what
is the revised probability that the current visitor is female? Should the
ParFore’s website display the special offer that appeals to female
visitors or the special offer that appeals to male visitors?
(.40)(.30)
(.40)(.30) + (.60)(.10) 0.6667
a.) What is the probability that a randomly selected adult user of the
Internet is age 50 or older?
b.) Given that an adult Internet user uses Facebook, what is the probability that he/she is age 18–49?
0.4212
.4212 +.2592 0.619
ditional information)?
nal information
0.21
𝜇 = 48 (3 / 60) = 2.4
f (0) =
47. During the period of time that a local university takes phone-in a.) What is the expected numbe
registrations,
calls come in at the rate of one every two minutes.
30 por hora.
𝜇 = 1 (5/2) = 5/2
8. In 2011, New York City had a total of 11,232 motor vehicle accidents that
occurred on Monday through Friday between the hours of 3 p.m. and 6 p.m.
(New York State Department of Motor Vehicles website, October 24, 2012).
This corresponds to mean of 14.4 accidents per hour.
8. In 2011, New York City had a total of 11,232 motor vehicle accidents that
occurred on Monday through Friday between the hours of 3 p.m. and 6 p.m.
(New York State Department of Motor Vehicles website, October 24, 2012).
This corresponds to mean of 14.4 accidents per hour.
𝜇
𝜇
e probability of receiving three calls in a 5-minute interval of time.
12
0.0907
0.0821
0.000045
b. Compute the probability that three or fewer passengers arrive in a oneminute period.
0.00045
0.0821
0.5488
c. Compute the probability of exactly one tornado during a day.
0.3293
a. What is the probability that Bob receives no tweets during his lunch hour?
0.0009
b. What is the probability that Bob receives at least 4 tweets during his lunch hour?
0.9182
c. What is the expected number of tweets Bob receives during the first 30 minutes of his lunch hour?
𝜇 = 7 por hora
𝜇 = 7/2 = 3.5 por 30 minutos 3.5 por 30
d. What is the probability that Bob receives no tweets during the first 30 minutes of his lunch hour?
0.0302
GUIA 2 - INTRO A PROBABILIDAD
a
p(N) no dar respuestas 0.04
p(C) corto en expectativas 0.26
p(E) llego a expectativas 0.65
p(A) paso expectitivas x
p(A) 1-(.004+0.26+.65) 0.05
p(A) 0.05 5%
b
p(N) no dar respuestas 0.04
p(C) corto en expectativas 0.26
p(E) llego a expectativas 0.65
p(A) paso expectitivas 0.05
p(E) ∪ P(C) 0.65+0.26 - (0.65 * 0.26) 0.6675
a
p(A) Sentir cukpa por comida 0.39
p(B) probabilidad culpable luz 0.27
p(C) probabilidad de ambas 0.12
a
p(A)= ACC sea campeon 10 veces campeon 0.5
p(B)= SEC sea cempeon 8 veces campeon 0.4
p(A) 0.5 50%
b
p(A)= ACC sea campeon 10 veces campeon 0.5
p(B)= SEC sea cempeon 8 veces campeon 0.4
c
p(A)= ACC sea campeon 10 veces campeon 0.5
p(B)= SEC sea cempeon 8 veces campeon 0.4
0.05 5%
d
p(A)= ACC sea campeon 10 veces campeon 0.5
p(B)= SEC sea cempeon 8 veces campeon 0.4
0.85 85%
e
p(A)= ACC sea campeon 10 veces campeon 0.5
p(B)= SEC sea cempeon 8 veces campeon 0.4
p(C) ambos equipos campeonato 0.85
15 15%
a
p(A) trabajo
p(B) personal
p(A) 50%
ss
AD
Probabilidad y Estadistica Quiz 7 Repaso Final
Guia 9 Problema 46
u 48 / hour
u 0.8 / min
Guia 8 Problema 34
a. f(x) = (1/20)*e^(-x/20)
b. f(x<=15) = 1 - e^(-15/20) = 0.527633 = 52.76%
c. f(x>20) = e^(-20/20) = 0.367879 = 36.79%
d. f(x<=5) = 1 - e^(-5/7) = 0.510458 = 51.05%
Guia 8 Problema 34
n 10
p 0.4
32. The automobile industry sold 657,000 vehicles in the United States
during January 2009 (The Wall Street Journal, February 4, 2009). This
volume was down 37% from January 2008 as economic conditions
continued to decline. The Big Three U.S. automakers—General Motors, Ford,
and Chrysler—sold 280,500 vehicles, down 48% from January 2008. A
summary of sales by automobile manufacturer and type of vehicle sold is
shown in the following table. Data are in thousands of vehicles. The non-U.S.
manufacturers are led by Toyota, Honda, and Nissan. The category Light
Truck includes pickup, minivan, SUV, and crossover models
Primer ejercicio
fabricante
estadounidense
N = fabricante
no
estadounidense
C = Automóvil
L = Camión
ligero
Students taking the Graduate Management Admissions Test (GMAT) were
asked about their undergraduate major and intent to pursue their MBA as a
full-time or part-time student. A summary of their responses follows.
a. Develop a joint probability table for these data.
Especialidad ingenieria otra
0.151 0.192
0.123 0.149
Total 0.274 0.341
e. Let A denote the event that the student intends to attend classes fulltime
in pursuit of an MBA degree, and let B denote the event that the student
was an undergraduate business major. Are events A and B independent?
Justify your answer.
sea A el evento de que el estudiante desee asistir a clases de tiempo
completo para la obtención de su maestría en administración y B el evento
de que tenga una especialidad licenciatura de negocios. ¿A y B son eventos
independientes? Explique
Para ver la independencia, debemos tener que
P (A)P(B)P (A)(B) = ?; de la tabla de probabilidades
conjuntas del inciso a tenemos
P(A) = 0.613
P(B) = 0.385
Por lo que P (A) P (B)= (0.387) (0.385)= 0.236
P(A*B)=0.270
Como P (A) P (B)(A B) =! P(A*B) los eventos no son independientes.
To better understand how husbands and wives feel about their finances,
Money Magazine conducted a national poll of 1010 married adults age 25
and older with household incomes of $50,000 or more (Money Magazine
website, December 14, 2014). Consider the following example set of
responses to the question, “Who is better at getting deals?
YO
Esposo 0.2752
Esposa 0.2871
Total 0.5624
Hay tres formas únicas en que Jamal Crawford anote al menos un tiro, que
anote el primero y falle el segundo, que falle el primero y anote el segundo,
o que anote ambos tiros. Como “fallar el tiro” es un complemento del
evento “anotar el tiro” P(fallar el tiro) = 1 – P(anotar el tiro) = 1 – 0.93 =
0.07. Por lo que:
P(anotar el tiro) P(fallar el tiro) = (0.93)(0.07) = 0.0651
P(fallar el tiro) P(anotar el tiro) = (0.07)(0.93) = 0.0651
P(anotar el tiro) P(anotar el tiro) = (0.93)(0.93) = 0.8649/0.9951
c. Podemos encontrar esta probabilidad de dos formas. Podemos calcular la
probabilidad de forma directa:
P(fallar el tiro) P(fallar el tiro) = (0.07)(0.07) = 0.0049
c. What is the probability that he will miss both shots?
P(anotar el tiro) = 0.58 para cada tiro por falta, por lo que la probabilidad de
que el centro de los Trail Blazers de Portland anote dos tiros consecutivos
por falta es P(anotar el tiro) P(anotar el tiro) = (0.58)(0.58) = 0.3364.
d. Late in a basketball game, a team often intentionally fouls an opposing
player in order to stop the game clock. The usual strategy is to intentionally
foul the other team’s worst free-throw shooter. Assume that the Portland
Trail Blazers’ center makes 58% of his free-throw shots. Calculate the
probabilities for the center as shown in parts (a), (b), and (c), and show that
intentionally fouling the Portland Trail Blazers’ center is a better strategy
than intentionally fouling Jamal Crawford. Assume as in parts (a), (b), and (c)
that two shots will be awarded.
Nuevamente, hay tres formas únicas en las que el centro de los Trail Blazers
de Portland puede anotar al menos un tiro. Puede anotar el primero y fallar
el segundo, fallar el primero y anotar el segundo o anotar ambos. Como el
evento “fallar el tiro” es complementario de “anotar el tiro”, P(fallar el tiro)
= 1 – P(anotar el tiro) = 1 – 0.58 = 0.42. Thus
P(anotar el tiro) P(fallar el tiro) = (0.58)(0.42) = 0.2436
P(fallar el tiro) P(anotar el tiro) = (0.42)(0.58) = 0.2436
P(anotar el tiro) P(anotar el tiro) = (0.58)(0.58) =0.3364/0.8236
Podemos encontrar la probabilidad de que el centro de los Trail Blazers de
Portland falle ambos tiros de dos maneras. Se puede calcular la probabilidad
de forma directa.
P(fallar el tiro) P(fallar el tiro) = (0.42)(0.42) = 0.1764
O se puede identificar el evento “fallar el tiro” como complemento de
“anotar al menos un tiro”, por lo que
P(fallar el tiro) P(fallar el tiro) = 1 - 0.9951 = 0.1764
Cometer falta contra el centro de los Trail Blazers de Portland es una mejor
estrategia que cometer falta contra Jamal Crawford.
37.A joint survey by Parade magazine and Yahoo! found that 59% of
American
workers say that if they could do it all over again, they would choose a
different career (USA Today, September 24, 2012). The survey also found
that
33% of American workers say they plan to retire early and 67% say they plan
to wait and retire at age 65 or older. Assume that the following joint
probability
table applies.
37. Sea S = el trabajador elige la misma profesión D = el trabajador elige una
carrera diferente E = el trabajador planea un retiro anticipado
a. What is the probability a worker would select the same career?
P(S) =1- P(D) =1-.59 = .41 como probabilidad marginal en la tabla
b.What is the probability a worker who would select the same career plans
to retire early?
P(E|S)0.2/41=0.4878
c. What is the probability a worker who would select a different career plans to retire early?
P(E|D)0.13/0.59=.2203
d. What do the conditional probabilities in parts (b) and (c) suggest about
the reasons workers say they would select the same career?
Probabilidades marginales:
Probabilidades marginales: P(U) = 0.4269 P(B) = 0.5731
P(C) = 0.4808 P(L) = 0.5192
f. Whatuna
Existe does the probability
probabilidad más information
alta, y por lotell you about sales?
tanto
una participación de mercado más grande,
para los fabricantes no estadounidenses. Sin
embargo, los fabricantes estadounidenses son
líderes en ventas en la categoría de camiones
ligeros.
Negocios Totales
0.27 0.613
0.115 0.387
0.385 1
segundo ejercicio
P(O | U) = 0.822
P(U) = 0.38
tercer ejercicio
Demorado Total
0.0696 0.3
0.0912 0.32
0.0676 0.38
0.2284 1
MI Conyuge Somos iguales
0.1257 0.101 0.502
0.1099 0.101 0.498
0.2356 0.202
Camion ligero total
193.1 280.5
148 376.5
341.1 657
17. The mean cost of domestic airfares in the United States rose to an all-time
high of $385 per ticket (Bureau of Transportation Statistics website, November 2,
2012). Airfares were based on the total ticket value, which consisted of the price
charged by the airlines plus any additional taxes and fees. Assume domestic
airfares are normally distributed with a standard deviation of $110. a. What is
the probability that a domestic airfare is $550 or more? b. What is the
probability that a domestic airfare is $250 or less? c. What is the probability that
a domestic airfare is between $300 and $500? d. What is the cost for the 3%
highest domestic airfares?
Err:522
The average return for large-cap domestic stock funds over the three years
2009–2011 was 14.4% (AAII Journal, February, 2012). Assume the three-year
returns were normally distributed across funds with a standard deviation of
4.4%.
a. What is the probability an individual large-cap domestic stock fund had a
three-year return of at least 20%?
a. En x = 20, 20-14.4/4.4= 1.27
P(z < 1.27) = 0.8980
P(x < 20) = 1 - 0.8980 = 0.1020
b. What is the probability an individual large-cap domestic stock fund had a
three-year return of 10% or less?
At x = 10, 10-14.4/4.4 =1.00
P(z<-1.00)=0.1587
p(x<10)=0.1587
c. How big does the return have to be to put a domestic stock fund in the
top 10% for the three-year period?
c. Un valor z de 1.28 corta un área de aproximadamente de 10% en la cola
superior
x = 14.4 + 4.4(1.28) = 20.03
Un rendimiento de 20.03% o más, ubicará al fondo de acciones nacionales en el
10% superior.
19. Automobile repair costs continue to rise with the average cost now at $367
per repair (U.S. News & World Report website, January 5, 2015). Assume that
the cost for an automobile repair is normally distributed with a standard
deviation of $88. Answer the following questions about the cost of automobile
repairs.
a. What is the probability that the cost will be more than $450?
. a. μ = 367 y σ = 88.
450 -367/88=0.94
b. What is the probability that the cost will be less than $250?
250-367/88=-1.33
c. What is the probability that the cost will be between $250 and $450?
P(z£ .94) - P(z£ -1.33) = .8264 -.0918 = 0.7346
d. If the cost for your car repair is in the lower 5% of automobile repair
charges, what is your cost?
Para que el costo de reparación del automóvil se encuentre en el 5% de cobros
más bajos debe ser de $222.24 o menos.
20. The average price for a gallon of gasoline in the United States is $3.73 and in
Russia it is $3.40 (Bloomberg Businessweek, March 5–March 11, 2012). Assume
these averages are the population means in the two countries and that the
probability distributions are normally distributed with a standard deviation of
$.25 in the United States and a standard deviation of $.20 in Russia.
a. What is the probability that a randomly selected gas station in the United
States charges less than $3.50 per gallon?
a. Estados Unidos: Media=3.73 desv=.25
3.5-3.73/0.25=-0.92
P(z<-0.92)=0.1788
p(X<3.5)=0.1788
b. What percentage of the gas stations in Russia charge less than $3.50 per gallon?
Rusia: = media= 3.40 desv=.20
En x = 3.50 = 3.50-3.40/0.20=0.5
P(z < 0.50) = 0.6915
So, P(x < 3.50) = 0.6915
69.15% de las gasolineras en Rusia cobran menos de $3.50 por galón
c. What is the probability that a randomly selected gas station in Russia charged
more than the mean price in the United States?
c. Se utiliza la media y la desviación estándar para Rusia.
En x = 3.73, 3.73-3.40/0.20=1.65
P z P z ( 1.65) 1 ( 1.65) 1 .9505 = .0495
P x( 3.73) =0.0495
22. Television viewing reached a new high when the Nielsen Company reported
a mean daily viewing time of 8.35 hours per household (USA Today, November
11, 2009). Use a normal probability distribution with a standard deviation of 2.5
hours to answer the following questions about daily television viewing per
household.
a. What is the probability that a household views television between 5 and 10
hours a day
Se utiliza Media = 8.35 y desv = 2.5
En x = 10, 10-8.35/2.5=.66
b. How many hours of television viewing must a household have in order to be in
the top 3% of all television viewing households?
En x = 5, 5-8.35/2.5= -1.34
P(5 ≤ x ≤ 10) = P(-1.34 ≤ z ≤ 0.66)= P(z ≤ 0.66) - P(z ≤ -1.34) =0.7454 - 0.0901 =
0.6553
La probabilidad de que un hogar vea la televisión entre 5 y 10 horas al día es 0.6553.
b. Encuentre el valor z que corta un área de 0.03 en la cola superior. Con una
probabilidad acumulada de 1 - 0.03 = 0.97, z = 1.88 proporciona un área de 0.03
en la cola superior de la distribución normal.
x = + z = 8.35 + 1.88(2.5) = 13.05 horas
Un hogar debe ver un poco más de 13 horas de televisión al día para ubicarse en
el 3% más alto de todos los hogares que ven televisión.
Un hogar debe ver un poco más de 13 horas de televisión al día para ubicarse en
el 3% más alto de todos los hogares que ven televisión.
En x = 3, 3 -8.35/2.25=-2.14
P(x>3) = 1 - P(z< -2.14) = 1 - 0.0162 = 0.9838
P(x>3) = 1 - P(z< -2.14) = 1 - 0.0162 = 0.9838
23. The time needed to complete a final examination in a particular college
course is normally distributed with a mean of 80 minutes and a standard
deviation of 10 minutes. Answer the following questions.
a. What is the probability of completing the exam in one hour or less?
60-80/10 = -2(z ≤ -2) = 0.0228. Por lo que P(x < 60) = 0.0228
b. What is the probability that a student will complete the exam in more than 60
minutes but less than 75 minutes?
60 -80/20=-2=2 = El área a la izquierda es 0.0228
En x = 75, 75-80/10 =-5
0.3085
P(60 x 75) = 0.3085 - 0.0228 = 0.2857
c. Assume that the class has 60 students and that the examination period
is 90 minutes in length. How many students do you expect will be
unable to complete the exam in the allotted time?
90-80/10=1
P(z ≤ 1) = P(x ≤ 90) = 0.1587
24. The American Automobile Association (AAA) reported that families planning
to travel over the Labor Day weekend would spend an average of $749 (The
Associated Press, August 12, 2012). Assume that the amount spent is normally
distributed with a standard deviation of $225.
Por lo tanto 15.87% de los estudiantes no terminará a tiempo.
(60) (0.1587) = 9.52
Se espera que sean 9 o 10 los estudiantes que no puedan concluir el examen a
tiempo
a. What is the probability of family expenses for the weekend being less that
$400?
The American Automobile Association (AAA) reported that families planning to
travel over the Labor Day weekend would spend an average of $749 (The
Associated Press, August 12, 2012). Assume that the amount spent is normally
distributed with a standard deviation of $225.
25. New York City is the most expensive city in the United States for lodging. The
mean hotel room rate is $204 per night (USA Today, April 30, 2012). Assume that
room rates are normally distributed with a standard deviation of $55.
a. What is the probability that a hotel room costs $225 or more per night?
225- 204/55=0.38
P (x ³ 225) = P (z³ .38) = 1 - P (z£ .38) = 1 - 0.6480 = 0.3520
La probabilidad de que una habitación de hotel cueste $225 o más por noche es
0.3520
b. What is the probability that a hotel room costs less than $140 per night?
140 - 204/55=-1.16
P (x < -1.16)= 0.1230