How you can quickly calculate the mean of the following test scores without adding the numbers.

Question

76,73,78,75

Answer 1

Mean = (76+73+78+75)/4 = 75.5

A quick way to calculate the mean is to take the difference between the largest and smallest number and divide it by 2; then add the results to the smallest number:

(78-73)/2 = 2.5, 73 + 2.5 = 75.5.