问题
单项选择题
If X has a normal distribution with μ=100 and σ=5, then there is approximately a 90% probability that:（）
A. P(90.2＜X＜109.8).
B. P(87.1＜X＜112.9).
C. P(91.8＜X＜108.3).
答案
参考答案：C
解析：
65 (5)=91.75 to 108.25 or P(91.75＜X＜108.25).