the average of 20 no.s is 14. the average of the 1st 10 is 15 and that of the next 9 is 13 find the last number.

Question

plz answer it

 

Answer 1

The sum of all 20 munbers is 14x20=280, the sum of first 10 numbers is 10x15 = 150, the sum of next 9 numbers is 9x13= 117. the last number equals 280 - (150+117) = 13.

 

Answer: 13.

Answer 2

The total of the 20 numbers is 20 x 14 = 280

 

The total of the 1st 10 numbers is 10 x 15 = 150

 

The total of the next 9 numbers is 9 x 13 = 117

 

The total of the 1st 19 numbers is 150 + 117 = 267

 

Therefore the last or 20th number is 280 - 267 = 13