趣味的数学-59
作者:gugeren+-
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趣味的数学-59
抽屉里放有红袜子和黑袜子2种颜色的袜子。随机抽取2只袜子时,抽出2只袜子都是红色的概率是1/2。
(a)抽屉里的袜子数量至少有几只?
(b)如果黑色袜子的数量是偶数,抽屉里的袜子数量至少又有几只?
【原文】
A drawer contains red socks and black socks. When 2 socks are drawn at random, the probability that both are red is 1/2.
(a) How small can the number of socks in the drawer be?
(b) How small if the number of black socks is even?