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