gmatbusters wrote:
If the probability is 1/6 that a die will turn up as one of the numbers from 1 to 6, what is the probability that in two rolls of that die, at least one of the rolls turns up as 6?
A) 1/36
B) 1/6
C) 11/36
D) 25/36
E) 5/6
Let P(A) denotes probability that roll turns up as 6.
Probability that at least one of the rolls turn up as 6= probability that two of the rolls turn up as 6+Probability of that 1st die turns up 6 and 2nd die turn a non-6+ probability that 1st die turns up as non-6 and 2nd die turns up as 6
=P(AA)+P(AA')+P(A'A)
=1/6*1/6+(1/6)(1-1/6)+(1-1/6)*(1/6)
=1/36+2*(1/6)*(5/6)
=1/36+10/36
=11/36
Ans. (C)
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PKN
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