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    How do I attempt this q.
    The probability that Ajita gets up before 6.30 am in the morning is 0.7
    The probability that she goes for a run in the morning is 0.35
    The probability that Ajita gets up after 6.30 am and does not go for a run is 0.22
    Let A represent the event that Ajita gets up before 6.30 am and B represent the event that she
    goes for a run in the morning.
    Find
    (a) P(A ∪ B), (2 marks)
    (b) P(A ∩ B′), (2 marks)
    (c) P(B | A). (3 marks)
    (d) State, with a reason, whether or not events A and B are independent. (2 marks)


    I have no idea on where to start,
    thanks
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    (Original post by Hi, How are you ?)
    I have no idea on where to start
    I drew a Venn Diagram
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    (Original post by Hi, How are you ?)
    How do I attempt this q.
    The probability that Ajita gets up before 6.30 am in the morning is 0.7
    The probability that she goes for a run in the morning is 0.35
    The probability that Ajita gets up after 6.30 am and does not go for a run is 0.22
    Let A represent the event that Ajita gets up before 6.30 am and B represent the event that she
    goes for a run in the morning.
    Find
    (a) P(A ∪ B), (2 marks)
    (b) P(A ∩ B′), (2 marks)
    (c) P(B | A). (3 marks)
    (d) State, with a reason, whether or not events A and B are independent. (2 marks)


    I have no idea on where to start,
    thanks
    Try drawing a Venn Diagram with two circles representing A and B.

    P(not A and not B) = 0.22 so the number 0.22 will go outside the circles.

    If you're still stuck, post what numbers you've managed to write in the diagram.
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    (Original post by notnek)
    Try drawing a Venn Diagram with two circles representing A and B.

    P(not A and not B) = 0.22 so the number 0.22 will go outside the circles.

    If you're still stuck, post what numbers you've managed to write in the diagram.
    Hi, so for A, i drew a diagram and so i done 1-0.22 = 0.78.
    b, 0.43
    c, 0.386 (3sf)
    d, not indp. as P(anb) does not equal P(a) * P(b), i.e. 0.27 does not equal 0.105
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    (Original post by Hi, How are you ?)
    Hi, so for A, i drew a diagram and so i done 1-0.22 = 0.78.
    b, 0.43
    c, 0.386 (3sf)
    d, not indp. as P(anb) does not equal P(a) * P(b), i.e. 0.27 does not equal 0.105
    All looks good
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    (Original post by Hi, How are you ?)
    Hi, so for A, i drew a diagram and so i done 1-0.22 = 0.78.
    b, 0.43
    c, 0.386 (3sf)
    d, not indp. as P(anb) does not equal P(a) * P(b), i.e. 0.27 does not equal 0.105
    Slightly faster method for d):

    For independent events A and B, P(B|A) = P(B).

    P(B|A) is your answer to c) and P(B) is given in the question.
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    (Original post by notnek)
    Slightly faster method for d):

    For independent events A and B, P(B|A) = P(B).

    P(B|A) is your answer to c) and P(B) is given in the question.
    Thanks
 
 
 
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