Asked by MNHS

The average of 10 numbers is 12. If one number is removed, the average is 11. What number is removed?
Answered by Bosnian
( a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 + a10 ) / 10 = 12 Multiply both sides by 10

a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 + a10 = 120


( a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 ) / 9 = 11 Multiply both sides by 9

a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 = 99


( a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 ) + a10 = 120

99 + a10 = 120 Subtract 99 to both sides

99 + a10 - 99 = 120 -99

a10 = 21


Number 21 is removed.





Answered by Reiny
the total of the 10 number is 120

solve

(120-x)/9 = 11
120-x = 99
-x = -21
x = 21