terry has a cube with sides labeled 1 through 6. he rolls the number cube twice. what is the probabilitythat the sum of the two rolls is a prime number, given that at least one of the rolls is a 1?

Answer 1

Primes are rolls of 2,3,5,7,11, but only 2,3,5,7 can be reached when there is a 1.

The number of rolls with a 1 is 11 out of the 36 rolls ( 2*5 (1-n )and double ones)

Out of those 1 + 2 + 2 + 2 will be prime. Therefore, the Probability is 7/11

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