Find the variance of the following distribution.

The time (in seconds) taken by a group of people to walk across a pedestrian crossing is given in the table below.

Calculate the variance and standard deviation of the data.

A group of 45 house owners contributed money towards green environment of their street. The amount of money collected is shown in the table below.

Calculate the variance and standard deviation.

Mean of 100 items is 48 and their standard deviation is 10. Find the sum of all the items and the sum of the squares of all the items.

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. Calculate the correct mean and standard deviation.