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 ?
6#jyfish
In mathematics and statistics, deviation is a measure of difference for interval and ratio variables between the observed value and the mean. The sign of deviation (positive or negative), reports the direction of that difference (it is larger when the sign is positive, and smaller if it is negative). The magnitude of the value indicates the size of the difference.
wiki上的
deviation就是观察值和平均值之间的差~~作者: jyfish 时间: 2012-5-18 08:34:17