We know that two odd numbers make an even number and two even numbers make another even number. So out of the first choice you have a 7/15 chance of getting it even and an 8/15 chance of getting it odd.
If you get the first one even, then the second one MUST also be even so you multiply 7/15 with itself.
If you get the first one odd, then the second one MUST also be odd so you multiply 8/15 with itself as well.
You should have:
(7/15) x (7/15)
and
(8/15) x (8/15)
By multiplying the top portions with each other and the bottom portions with each other you get:
49/225 and 64/225 respectively.
Add both fractions together to get your answer.
Your answer should be (64+49)/225 = 113/225
Your answer is 113/225.
