Total numbers are 50. So, we are actually subtracting 53_50 from the sum of 50 terms. We can get the new sum as negative number by using the formula of mean.

This statement is the defination of one of the measure of central tendency.

Think about those which we can not be used to represent graphically.

Use the basic formula to find the mean of this data.

Use the formula of mean and find the total sum of five numbers and then sum of the remaining four numbers.

Think about the total sum of observations for the mean 15 and mean 20.

Find the total sum of original observations by using the formula of mean. Then, add the difference of 70 and 170 to the orignal sum. Then, find the final mean.

Think about those which we can not be used to represent graphically.

Think about the basic formula of mean.

Find the total sum of all 15 observations. Then, find the total of first 8 and last 8 observations.