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    WST ct3 Mon

    Uploaded by

    Vuledzani Mutshinyalo
    statistic and probability class test 3

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

    WST ct3 Mon

    Uploaded by

    Vuledzani Mutshinyalo
    3 views2 pages
    statistic and probability class test 3

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    wst ct3 mon

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    statistic and probability class test 3

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    3 views2 pages

    WST ct3 Mon

    Uploaded by

    Vuledzani Mutshinyalo
    statistic and probability class test 3

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 2

    WST111 Class Test 3/ Klastoets 3

    INITIALS & SURNAME / MEMO


    VOORLETTERS & VAN
    STUDENT NUMBER/ STUDENTENOMMER
    SIGNATURE/ HANDTEKENING
    Round final answers to two decimal places./ Rond finale antwoorde af tot twee desimale plekke.

    1. Five people claim that they can distinguish Pepsi Cola from Coca Cola by taste. Each is given a
    sample of both, and asked to identify which is Pepsi Cola. If all the people are in fact guessing,
    what is the probability that:
    Vyf mense beweer dat hulle deur smaak kan onderskei tussen Pepsi Cola en Coca Cola. Elkeen
    word voorsien van ‘n slukkie van beide en gevra om die Pepsi Cola te identifiseer. Indien al die
    mense eintlik aan die raai is, wat is die waarskynlikheid dat:

    (a) all 5 guess correctly?/ al vyf reg raai?

    5
    1
     
    2

    (b) 3 out of 5 guess correctly?/ 3 uit 5 reg raai?

     5  / 2 5 = 0.3125
     
    3

    (3)
    2. Suppose A, B and C are three events in a sample space, and that P(A)=0.6, P(B)=0.2,
    P(B ∪ C)=0.3 and P(A|B)=0.5. Determine:
    Veronderstel A, B en C is drie gebeurtenisse in ‘n steekproefruimte, en dat P(A)=0.6, P(B)=0.2,
    P(B ∪ C)=0.3 en P(A|B)=0.5. Bepaal:

    a)
    P(B|A)=P(A∩B)/P(A) Def. 2.9
    =P(A|B)P(B)/P(A) Th.2.5
    =(0.5x0.2)/0.6=0.167

    (3)
    b) P(C) if B and C are mutually exclusive / P(C) indien B en C onderling uitsluitend is

    P(B ∪ C)=P(B)+P(C) Th.2.6


    ∴P(C)=0.3-0.2=0.1

    (2)
    c) P(C) if B and C are independent / P(C) indien B en C onafhanklik

    P(B∩C)=P(B)P(C)
    but P(B ∪ C)=P(B)+P(C)-P(B∩C)
    and P(B)+P(C)- P(B ∪ C)=P(B)P(C) if B and C independent (Def.2.10)
    Then P(C)[1-P(B)]=0.3-0.2
    so that P(C)=0.1/(1-0.2)=0.125

    (2)
    [10]

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