Question

the arithmetic mean of 5 data is 20 if one of the data is deleted then arithmetic mean becomes 15.Find out the deleted one​

Answer 1

mean= 20

number of terms = 5

Sum of terms= 20×5

= 100

now, new mean= 15

number of terms= 4

Sum of terms= 15×4

= 60

The difference between the means= 100-60

= 40

The deleted number is 40.