John rolls a number cube twice. what is the probability that the sum of the 2 rolls is less than 7, given that the first roll is a 1? one over six one over three one over two five over six

 The correct option is (d) five over six.

Step-by-step explanation:  Given that John rolls a number cube twice. We are to find the probability that the sum of the 2 rolls is less than 8 given that he first roll is a 1.

The sample space of an event of rolling a cube is

S = {1, 2, 3, 4, 5, 6}.

That is, n(S) = 6.

Now, let 'A' be the event that the sum of the two rolls is less than 7, then

A = {1, 2, 3, 4, 5}.

That is, n(A) = 5.

So, the probability of happening of event A is given by

Thus, the required probability is five over six.

Option (d) is correct.

b

step-by-step explanation: