AMATH Statistics
AMATH Statistics
AMATH Statistics
0 5
1 q
2 6
3 4
4 7
Table 1
Find
a) the maximum value of q if the mode is 4,
b) the range of values of q if the median is 2
Mass (kg) 20 - 24 25 - 29 30 - 34 35 - 39 40 - 44
Number of students 10 22 29 p 15
Table 2
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a) What is the best measure of central tendency to represent the set of data?
Give your reason.
b) An athlete whose score is 97 decided to withdraw from the tournament and he was
replaced with another athlete whose score is 210.
What is the best measure of central tendency to represent the new set of data?
Give your reason.
Score 6 ? 8 ? 13 15 18
Table 1
a) Given the interquartile range of the score is 7 and the mean score is 11, find the
score of Zahidah and Naliza.
b) Find the standard deviation of the score.
c) The students sat for another written quiz and each of them managed to double their
score. State the new mean and the new variance.
2
1 A set of data consists of 8, 2, 7, x - 2, 5 and 4. Given the mean is 5.5, find
a) the positive value of x,
b) the median using the value of x in (a).
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Table 2
a) Which sports house shows the most consistent achievement in the competition?
Give reason for your answer.
b) State the variance for the sports house stated in 2(a).
Table 11
2
Rahim calculated the variance and found it to be -406.4036 kg . Since variance should be
positive, Rahim suspected that he forgot to square one of the data while calculating the sum
of squares of the masses.
Given that other calculation in obtaining the variance were correct, find whose mass was not
squared by Rahim. Show your working clearly.
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4. Table 4 shows a frequency distributions of the outcome of a power consumption study of 100
houses in a residential park.
Power
Consumption 80-89 90-99 100-109 110-119 120-129 130-139 140-149
(kWh)
Number of
7 14 17 19 21 13 9
houses
Table 4
22 Given a set of data consists of 5 numbers of a, b, c, d and e. Given the median is 8 and the
variance is 4. Another set data consists 3a + 2, 3b + 2, 3c + 2, 3d + 2 and 3e + 2. Calculate
the value of median and variance.
5 Table 5 shows times recorded, t minutes, for a group of 200 students to complete a
Mathematics Quiz.
Time (minute), t 16 - 20 21 - 25 26 - 30 31 - 35 36 - 40 41 - 45
Number of students 62 88 16 13 11 10
Table 5
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b) Due to the technical error, all students took 5 minutes less than the times recorded in
Table 5. Explain the effects this would have on each of the value found in 5(a).
22 An integer set consists 3, r and 8. The variance for this integer set is .
23 Table 23 shows the marks for 30 students in a monthly exam that consists 26 questions.
Score 4-9 10 - 15 16 - 21 22 - 27
Frequency 6 q m 6
Table 23
Given that the median for the data is 16.59. Express q in terms of m.
Hence, if q = 7, find the value of first quartile.
5 Table 5 shows the frequency distribution of the pH values of soil samples taken from two
orchards.
4.4 – 4.8 3 2
4.9 – 5.3 5 7
5.4 – 5.8 5 5
5.9 – 6.3 10 12
6.4 – 6.8 12 8
6.9 – 7.3 5 6
Table 5
Find the mean and standard deviation of the distribution in each orchards. Based on the
values obtained, compared the better soil orchard.
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6 The first set of data x, …, 14, is arranged in ascending order, so does the second data 16, …,
y. Each set of data has 6 values. When the sets of data are combined, x, …, 14, 16, …, y,
the new median is m and the new standard deviation is q.
18 The set of data 2, 2p, 10, p + 10, 18, 3p + 14 that are arranged in ascending order has mean
k. Given that the interquartile range is 12.
a) Express p in terms of k.
b) Find the value of p.
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2 Table 2 shows the frequency distribution of the marks obtained by N students in a test.
0–9 4
10 – 19 9
20 – 29 5
30 – 39 p
40 - 49 2
Table 2
a) Given that the median mark is 23.5, find the value of p and of N.
b) Using a scale of 2 cm for 10 marks on the horizontal axis and 2 cm for 1 student on
the vertical axis, draw a histogram to represent the frequency distribution. Find the
mode of the distribution.
14 Table 1 shows the frequency distribution of the marks for Additional Mathematics in an exam
for a group of students.
1 – 20 3
21 – 40 8
41 – 60 9
61 – 80 8
81 – 100 m
Table 1
Given the minimum mark for 75% of the total students is 70.5 marks and m < 9. Find
a) mode of the marks,
b) value of m.
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2 Diagram 1 shows a histogram which represents the distribution of marks for Mathematics
obtained by students of Bestari Class in an examination.
Diagram 1
a) Calculate
(i) the mean mark,
(ii) standard deviation for marks of the students in the class.
b) If the mark of each student is increased by 2, state the variance of the new marks
obtained by the students in the class.
b) Given the standard deviation of the numbers is √ , find the new variance of the
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23 Table 1 shows the frequency distribution of the scores of a group of students in a test.
Score 1 - 10 11 - 20 21 - 30 31 - 40
Frequency 4 14 k 12
Table 1
Scores ≤5 ≤ 10 ≤ 15 ≤ 20 ≤ 25 ≤ 30 ≤ 35
Number of pupils 0 3 8 17 28 36 40
Table 1
Supervisor 1 3500
Accountant 1 3000
Clerk 3 x
Table 21
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Diagram 5
20 – 29
30 – 39
40 – 49
50 – 59
60 – 69
b) Find
(i) mean
(ii) variance and standard deviation
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24 Given 4 and 7 respectively are mode and min for a set of data 3, 4, 4, 6, 10, 12, 12, m, n, with
m > n. Find
a) the value of p and of q
b) median
25 The quartile range and the standard deviation of a set of data are 6 and 2.4 respectively.
If each value in the data is divided by 3 then added by 8, find
a) the new quartile range
b) the new variance.
4 A teacher wants to select either Ahmad or Luqman to represent the school in a 100 metre
swimming event. Table 1 shows the time taken for each student to complete the swimming
events in six trials.
Table 1
2
a) Calculate the standard deviation in second , for the time taken by Ahmad and
Luqman to complete the 100 metre swimming event.
b) The teacher will select the student with the best and more consistent performance.
Based on the answer in 4(a), state which student will represent the school in the 100
metre swimming event and give a brief reason.
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20 A set of six numbers has a mean of 18 and a standard deviation of √ . When 25 is added to
this set, the mean increases by 1. Find the new variance.
23 The mean and median of 50 pieces of cables are 2.56 m and 2.39 m respectively. After
checking, it is found that a cable of length 4.16 m is wrongly recorded as 3.61 m. Based on
the above information, find the actual mean and median.
3 Hafiz and Syafiqah are two best students in 5 Alpha in the Mid Year Examination. Hafiz
obtained an average marks of 66.8 and a standard deviation of 11.36 for the five subjects
while Diagram 3 shows Syafiqah’s results for each of the subject.
Diagram 3
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3 A set of six numbers has a mean of 30. When two numbers a and (a – 6) are added to the
set, the mean becomes 27. Find the value of a.
25 Table 25 shows the number of books borrowed by a group of students in a certain week.
Table 25
2
20 A set of data consists of 9, 6, 5, x – 2 and 8. Given the mean is 7, find
a) the positive value of x,
b) the variance using the value of x in (a).
21. Table 21 shows the distribution of the scores obtained by 40 students in a quiz competition.
Marks 0 5 10 15 20
Number of students 2 9 15 11 3
Table 21
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Scores 10 - 19 20 - 29 30 - 39 40 - 49 50 - 59
Number of students 5 8 k 11 4
Table 3
a) It is given that the first quartile of the scores is 25.75, find the value of k.
b) Find the mean of the scores.
c) Hence, find the standard deviation.
14 The sum and the sum of squares of Miss Chua’s monthly income for the first six months in the
year 2015 are RM 12 240 and RM 24 975 000 respectively. Find the standard deviation of
this monthly income within those six months.
a) As the Singapore’s coach of 100 m, Mr R will held a series of intensive training and
obtain data for two of the best athletes who are expected to represent the country.
Table 2 shows the time recorded by two athletes, A and B, in the 100 m event during
th
the qualifying session. New rules of 30 SEA Games, specify only one athlete will
represent the country.
Athlete Time (second)
A 10.38 10.40 10.60 10.70 10.82
B 10.48 10.50 10.60 10.62 10.72
Table 2
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th
By using data in Table 2, which athlete qualifies to compete in the 29 SEA Games?
th
b) Table 3 shows time entry for gold medal winner of men final 100 m in the 29 SEA
Games.
Table 3
Athlete who was selected by Mr R has trained intensively and can reduce the timing
of 0.35 s constantly for all entries which appear in Table 2. Does the new time entry
allowed him to win the gold medal if Khairul Hafiz Jantan maintain the time record in
th th
30 SEA Games as 29 SEA Games, as shown in Table 3.
1 A set of fifteen numbers x1, x2, x3, …, x15 has a standard deviation of √ .
Find
a) the value of ∑( ̅) ,
1 Table 1 shows the frequency distribution of the mass of a group of students in a class.
40 – 49 6
50 – 59 h
60 – 69 18
70 – 79 16
80 – 89 6
Table 1
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a) It is given that the third quartile mass of the distribution is 74.5 kg. Calculate the
value of h.
b) Using a scale of 2 cm to 10 kg on the horizontal axis and 2 cm to 2 students on the
vertical axis, draw a histogram to represent the frequency distribution of the mass.
Hence, estimate the mode of the mass.
c) What is the mode mass if the mass of each student is increased by 4 kg?
2 Encik Syukri pays RM x income tax every month for his tax assessment in the year 2015.
Table 2 shows the sum and the sum of squares of x.
∑ 30 000
∑ 75 019 200
Table 2
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25 Table 25 shows the frequency distribution for the marks obtained by a group of students.
Score Frequency
15 – 19 1
20 – 24 8
25 – 29 6
30 – 34 5
35 - 39 4
Table 25
10 The mean of a set of data 1, x, 2x, 9, 10 and 16 is y. If each value in the set is decreased by
P 4 k 36
Q 5 150 m
Table 5
a) Given the mean age of the members of group P is 48, find the value of k.
b) (i) For group Q, ∑( ̅) , find the value of m.
(ii) Hence, find the sum of squares of the age group Q members.
c) Calculate the mean and the variance of the combined groups age.
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