Posted by **MNHS** on Wednesday, November 14, 2012 at 2:10am.

The average of 10 numbers is 12. If one number is removed, the average is 11. What number is removed?

- math 1 -
**Bosnian**, Wednesday, November 14, 2012 at 9:42am
( 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.

- math 1 -
**Reiny**, Wednesday, November 14, 2012 at 10:14am
the total of the 10 number is 120

solve

(120-x)/9 = 11

120-x = 99

-x = -21

x = 21

## Answer this Question

## Related Questions

- Math - The mean of five numbers is 8. If one of the numbers is removed from the ...
- math - Does anyone know how to explain mean, median, mode and range mean?? mean-...
- math - I am looking for the median, I believe it is 39 am I correct? 26, 30, 38...
- maths - 1).Last year, a shopkeeper sold an average of 7 cartons of apples from ...
- Math - The average of five number is 56. Four of the numbers are the same. The ...
- Programming - I suppose to write a program that calculates the average of up to ...
- Math - The average of 3 numbers is 45. If one of the numbers is 43, what is the ...
- math - average of 6 numbers is 19.A seventh number is added and the new average ...
- MATH - The average of 30 numbers is 65. If one of these numbers is 65, the sum ...
- MATH. - The average of two numbers is x. If one of the numbers is 3m-1, then the...

More Related Questions