what is the probabilty of rolling a double on a first or second roll?

Question

with two dice

Answer 1

There are six ways to get doubles out of 36 possible rolls.
6/36 = 1/6. (Think of the first die. The chance is 1/6 that the second die matches.)

P(doubles on a single roll) = 1/6

So you could get doubles on the first roll (1/6)
Or you could get non-doubles, then doubles on the second roll (5/6 x 1/6).

The sum is 6/36 + 5/36 = 11/36

Another way to compute this is:

P(A or B) = P(A) + P(B) - P(A and B)

= 1/6 + 1/6 - 1/36
= 6/36 + 6/36 - 1/36
= 11/36

Answer 2

1/6 chance on any roll
so 5/6 no double first roll
double first or second = 1/6 + (1/6)(5/6) = 11/36

Answer 3

The probability of that happening is 1/12. Maybe even 2/12s I'm not sure, I haven't done probability questions in a long time.