Posted by jake on .
Suppose x is a random variable with mean and standard deviation. If a large number of trials is observed, at least what percentage of these values is expected to lie beween mean2(standard deviation) and mean + 2(standard deviation)
could someone help me i'm so lost? thank you sooooo much!!!

math 
bobpursley,
Memorize it. Two standard deviations contain 95 percent of the population.