Tanya prepared 4 different letters to be sent to 4 different addresses. For each letter, she prepared an envelope with its correct address. If the 4 letters are to be put into the 4 envelopes at random, what is the probability that only 1 letter will be put into the envelope with its correct address?

• A.

$\frac{1}{24}$

• B.

$\frac{1}{8}$

• C.

$\frac{1}{4}$

• D.

$\frac{1}{3}$

• E.

3/8

• sylvie

总共是有4！=24种方式来放置地址；只有1个地址放对，其他3个地址放错，假设第一个是放对了的就有4种方式，第二个放错只有2种方式，那么到了第三个和第四个的时候就只有一种方式。那么4*2/24=1/3

2019-03-04 14:01:54