The mean and standrad deviation of 100 items are 50, 5 and that of 150 items are 40, 6 respectively.
What is the variance of all 250 items?

The mean and standrad deviation of 100 items are 50, 5 and that of 150 items are 40, 6 respectively. What is the combined mean of all 250 items?

The mean and standrad deviation of 100 items are 50, 5 and that of 150 items are 40, 6 respectively. What is the combined standard deviation of all 250 items?

Mean and standard deviation of 100 items are 50 and 4 respectively. The sum of all squares of the items is

Mean and standard deviation of 100 items are 50 and 4, respectively . Find the sum of all the item and the sum of the squares of the items.

If mean and standard deviation of 100 items are 50 and 4 respectively the find the sum of all the item and the sum of the squares of item.

The mean and standard deviation of 20 items are found to be 10 and 2 respectively. At the time of checking it was found that an item 12 was wrongly entered as 8 . Calcualte the correct mean and standard deviation.