感觉OG中给的那套题里的数学还是有一定难度的啊!!
1. 7.A list of numbers has a mean of 8 and a standard deviation of 2.5. If x is a
number in the list that is 2 standard deviations above the mean, what is the
value of x ?
答案:13
2. 14.The random variable X is normally distributed. The values 650 and 850 are at the 60th and 90th percentiles of the distribution of X, respectively.
Quantity A Quantity B
The value at the 75th 750
percentile of the
distribution of X
3. 17.Let S be the set of all positive integers n such that n2 is a multiple of both
24 and 108. Which of the following integers are divisors of every integer n
in S ?
Indicate all such integers.
A 12
B 24
C 36
D 72
4. 19.A random variable Y is normally distributed with a mean of 200 and a standard deviation of 10.
Quantity A Quantity B
The probability of the event 1/6
that the value of Y is
greater than 220 作者: caoys2012 时间: 2012-7-25 22:34:54