[問題]新pp問題7

[mht]

7.A basket contain 5 apples of which 1 is spoiled and the rest are good. If H is to select 2 apples from the basket simultaneously and at random, what is the probility that the 2 apples selected will include the spoild apple?
(不是1/5呀?不知機率算式分子為?) Ans. 2/5

[clbb]

4/C(5,2)=4/10=2/5