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by ratindasgupta » Tue Aug 28, 2007 1:05 pm
There are two ways you can solve this question

One is the dependant probability format.
If two non defective pens have to be selected, the probability of selecting first one is 9/12 and the probability of selecting the second one is 8/11.

9/12 x 8/11 = 6/11

The second method is using the hypergeometric probability formula which is (number of favourable events)/(total number of events).

number of favourable events = 9C2
total number of events = 12C2

9C2/12C2 = 6/11
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by magical cook » Tue Aug 28, 2007 2:42 pm
yes OA is 6/11. thanks.
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by crackitpal » Wed Aug 29, 2007 11:05 am
is this question from PS practice questions available from this site ?
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