The standard deviations of two sets containing 10 and 20 members are 2 and 3 respectively measured from their common mean 5. Find the S.D. for the whole set of 30 members

The arithmetich mean and standard deviation of a data of nine numbers are 13 and 5 respectively. If 3 is incoluded as the 10th item of the data, then the variance of the data of ten number is

The standard deviation of 5, 12, 3, 18, 6, 8, 2, 10 is

The arithmetic mean and standard deviation of a set of 9 items are 43 and 5 respectively , If an item of value 63 is added to that set , find the new mean and standard deviation of 10 item set given

The arithmetic mean and standard deviation of a set of 9 items are 43 and 5 respectively. If an item of value 63 is added to that set, then the new standard deviation of 10 item set given is

For a group of 100 observations, the arithmetic mean and standard deviation are 8 and sqrt(10.5) respectively. The mean and standard deviation of 50 items selected from these 100 observations are 10 and 2 respectively. Then the standard deviation of the remaining 50 observation is

The mean and the standard deviation of data of 8 items are 25 and 5 respectively. If two items 15 and 25 are added to this data, then the variance of the new data is