Please do the correction needed in here. Mean and Standard deviation calc.

Let us say that a company has recorded daily salaries of 21 people according to their ranks. Here is the data set= 9, 65, 61, 62, 53, 55, 60, 70, 64, 56, 58, 58, 62, 62, 68, 65, 56, 59, 68, 61, 67 Seconds Frequency 51-55 56-60 61-65 66-70 Median group is the one in which the middle value lies. In this case it lies in the (61-65)th group. After putting values in the formula of estimated mean - 8 ) means don't count as Tool unless You do S.D. cale as well Estimated mean= 60.5 + (21/2)-9/8 * 5 Estimated mean= 61.4375