Solution: The standard deviation is used in conjunction with the mean to numerically describe distributions that are bell shaped. The mean measures the center of the distribution, while the standard deviation measures the spread of the distribution.
In normal distribution (bell shaped distribution) , the mean and standard deviation are used to describe its distribution. The mean measures the center of the distribution, while the standard deviation takes care of the spread of the distribution.
The mean of the normal distribution is [tex]\mu[/tex] and the standard deviation is [tex]\sigma[/tex]