Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 29 views

    Probability 2 Trees

    Uploaded by

    Espee
    1) A tree diagram is constructed showing the probabilities of a randomly selected male and female from an IB group being in SL or HL maths. 2) Probabilities are calculated for: both doing HL maths (18/100), both doing SL maths (28/100), one doing HL and one SL (54/100), and the male doing HL while the female does SL (42/100).

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Probability 2 Trees

    Uploaded by

    Espee
    29 views6 pages
    1) A tree diagram is constructed showing the probabilities of a randomly selected male and female from an IB group being in SL or HL maths. 2) Probabilities are calculated for: both doing HL maths (18/100), both doing SL maths (28/100), one doing HL and one SL (54/100), and the male doing HL while the female does SL (42/100).

    Copyright

    © © All Rights Reserved

    Available Formats

    PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    1) A tree diagram is constructed showing the probabilities of a randomly selected male and female from an IB group being in SL or HL maths. 2) Probabilities are calculated for: both doing HL maths (18/100), both doing SL maths (28/100), one doing HL and one SL (54/100), and the male doing HL while the female does SL (42/100).

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    29 views6 pages

    Probability 2 Trees

    Uploaded by

    Espee
    1) A tree diagram is constructed showing the probabilities of a randomly selected male and female from an IB group being in SL or HL maths. 2) Probabilities are calculated for: both doing HL maths (18/100), both doing SL maths (28/100), one doing HL and one SL (54/100), and the male doing HL while the female does SL (42/100).

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 6

    Probability 2: constructing tree

    diagrams

    IB Studies
    AND and OR 1
    A bag contains 3 red counters b) Find the probability that 2
    and 2 blue counters. A counter blue counters are picked.
    is picked at random, then
    replaced in the bag. A counter P(blue)  P(blue) 4
    2 2 
    is then chosen again. 25
    = 
    5 5
    a) Find the probability that 2 c) Find the probability that the
    red counters are picked. 2 counters are picked are the
    same colour.
    You want: red AND red
    You want:
    Relace the AND with  . Red AND red OR blue AND blue
    Re place the OR with +.
    P(red)  P(red)
    P(red)  P(red) + P(blue)  P(blue)
    3 3 9    
    =    3 3  2 2 13
    5 5 25 =       
     5 5  5 5 25
    AND and OR 2
    A tired maths teacher reaches b) two red socks,
    into her sock draw in the 3 2
    morning. She has 5 black and 3 P(red)  P(red)= 
    red socks in the draw. She 8 7
    picks two socks at random. 6
    Find the probability that she 
    picks,
    56

    a) two black socks, c) matching socks,


    Note that this is a question
     5 4   3 2  26
    without replacement, so be
          
    careful with the second  8 7   8 7  56
    probability.
    d) socks of different colours.
    5 4
    P(black)  P(black)= 
    8 7 26 30
    1 
    20 56 56

    56
    Tree diagrams - construction
    A bag contains 3 red counters and 2 blue counters. A counter is
    picked at random, then replaced in the bag. A counter is then
    chosen again.
    Show this information on a tree diagram.
    1st choice 2nd choice
    9
    3 red r AND r 
    25
    3 5
    red
    5 2 6
    blue r AND b 
    5 25
    3
    red 6
    5 b AND r 
    2 25
    blue
    5
    2 4
    blue b AND b 
    5 25
    Tree diagrams - reading a table
    9 Always fill in the
    25 probabilities on at the end
    of the branches, keep the
    6 denominators the same and
    25 ensure the total is 1.
    6
    25 This makes answering
    questions much easier.
    4
    25
    Find the probability that
    c) the 2 counters picked 13
    9 are of the same colour,
    a) 2 red counters are 25
    picked,
    25
    d) the 2 counters are
    picked are of different
    12
    b) blue counters are 4
    picked, colours. 25
    25
    Question
    An IB group has 10 males and 10 females. 4 males do SL maths and 6
    do HL maths. 7 females do SL and 3 do HL maths. One male and one
    female are chosen at random and their level of maths is noted.
    a) Construct a tree diagram for this data.
    Hence, calculate the probability
    Male Female 28
    7
    SL that when a male and female are
    100 chosen at random,
    10
    4 SL 18
    12
    b) both do HL,
    10 3
    HL 100 100
    10
    42 c) both do SL, 28
    6 7 SL
    10 HL 10 100 100

    d) one does HL, 54


    3 18
    HL 100 and one does SL. 100
    10
    e) the male does HL, 42
    the female does SL. 100

    You might also like