NO.PZ2019040801000019
问题如下:
A survey shows that 30% of the offices have printers in this building. Assuming a binomial probability distribution, what is the probability that exactly three businesses will have a printer in a random selection of five businesses?
选项:
A. 0.0338.
B. 0.0576.
C. 0.1323.
D. 0.1424.
解释:
C is correct.
考点:二项分布
解析:5个办公室里3个有打印机的概率是:
[5! / 3!(5-3)!]*(0.3)3*(0.7)5-3 = 10*(0.027)*(0.49) = 0.1323
为什么要乘以0.7的2次方