A basket has 5 apples, one is spoiled. If Henry picked 2 apples simultaneously and at random, what is probability that the 2 selected apples will include the spoiled one.
a. 1⁄5
b. 2⁄10
c. 2⁄5
d. 1⁄2
e. 3⁄5
为什么我算的是1/5呢?我是这样算的C4 1/(C51*C4 1)
错在哪里了呢?作者: season5924 时间: 2011-5-17 20:02