The mean of 20 numbers is 18. If 3 is added to each of the first ten numbers, find the mean of the new set of 20 numbers.
Given,
Mean of 20 numbers = 18.
Sum of these numbers = 20 × 18 = 360.
When 3 is added to each of the first ten numbers,
Total increment in sum = 10 × 3 = 30.
New sum becomes = 360 + 30 = 390
Mean of New set of numbers =