Question

The average of 20 number is 14. The average of the first 10 is 15 and that of the next 9 is 13. What is the last number?

Answer 1

Average of the 20 numbers = 14

Sum of the 20 numbers = 14 x 20 = 280

Average of the first 10 numbers = 15

Sum of the first 10 numbers = 15 x 10 = 150

Average of the next 9 number = 13

Sum of the next 9 numbers = 13 x 9 = 117

Sum of the first 19 numbers = 150 + 117 = 267

Last number = 280 - 267 = 13

Answer: The last number is 13