Question: probability of exactly 1 defective pen in the box = ?
(1) The probability that all the pens in the box are not defective is 96 percent:
In this case, we can say that the probability of atleast 1 pen is defective = 4%
But we cant not say the probability of exactly 1 pen is defective. Hence, Insuff.
(2) The probability that there is more than 1 defective pen in the box is 3 percent:
In this case, we can say that the probability of atmost 1 pen is defective = 100 - 3 = 97%
However, this includes = the probability of 1 pen is defective + the probability of no pen is defective. Hence, insuff.
(1) & (2) together,
from 2: probability of atmost 1 pen is defective = 97%
from 1: probability of all the pens are not defective = 96%
Hence, probability of exactly1 pen is defective = 97-96 = 1%
Ans: C
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