how to find the variance: variance is calculated by taking the differences between each number in the data set and the mean, then squaring the differences to make them positive, and finally dividing the sum of the squares by the number of values in the data set.

so we have the mean as (147+141+120+124+128)/5=660/5=132

so we have 132-147=-15, 132-141=-9, 132-120=12, 132-124=8, 132-128=4

(-15)^2=225, (-9)^2=81, 12^2=144, 8^2=64, 4^2=16

so 225+81+144+64+16=530

530/5=106

check this please