If the mean of a normal probability distribution is 400, and the standard deviation is 10, approximately 95 percent of the values of the distribution lie between what two values?

Answer by  azertyken (19)

The answer is between 380 and 420, i.e. 20 on each side of the mean of the distribution. In other words, for a confidence value of 95%, the extremes of the range are 2 standard deviations away from the mean. For a 66% percent, this would be 1 standard deviation.

Answer by  sheharyar (6)

If there are 'n' number of numbers in the above stated set, the mean is equal to the sum of all the numbers divided by 'n'.If the standard deviation of these numbers is 10, it means that 95% of the values lie between 390 and 410.