Hello, babbagandu!

Box 1 contains 25 computer diskettes: 5 DD and 20 HD.

Box 2contains 15 diskettes: 10 DD and 5 HD.

A box is selected at random and then two diskettes are chosen randomly from the selected box.

What is the probability that both diskettes are HD?

. . Hence: .

. . Hence: .

Therefore: .