Question

The average of 11 numbers is 21 . The average of seven of those numbers is 25. What is the average of the remaining four numbers?

Answer 1

\[(7*25+x*4)/11=21\]
\[4x=231-175=56\]
x=14, so the average of the remaining 4 numbers is 14

Answer 2

total of the 11 number = 11x21 = 231
total of the seven number = 25*7 = 175
total of the 4 number = 231-175 = 56
average required = 56/4 = 14

Answer 3

x1 + x2 + x3 ......+x11 = 21*11
x1 + x2 ...... +x7 = 25*7
Therefore
x8 + x9 + x10 + x11 = 21*11 - 25*7
Average = (21*11 - 25*7 )/ 4
=56/4 = 14