Question 238550: How do u do these questions:
A lot contains 12 items of which 4 are defective. Three items are drawn at random from the lot one after the other. Find the probability p that all three are non-defective.
A man visits a couple who have two children. One of the children, a boy, comes into the room. Find probability p that the other is also a boy if (i) the other child is known to be younger (ii) nothing is known about the other child.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! How do u do these questions:
A lot contains 12 items of which 4 are defective. Three items are drawn at random from the lot one after the other. Find the probability p that all three are non-defective.
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# of ways to get 3 non-defective = 8C3 = (8*7*6)(1*2*3) = = 56
# of ways to get 3 unrestricteded = 12C3 = (12*11*10)/(1*2*3) = 220
P(3 non) = 56/220 = 0.2545
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A man visits a couple who have two children. One of the children, a boy, comes into the room. Find probability p that the other is also a boy if (i) the other child is known to be younger
Age has nothing to do with it; neither does the fact that the 1st child
to appear is a boy.
The answer is 1/2
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(ii) nothing is known about the other child.
It's still 1/2
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Cheers,
Stan H.
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