SOLUTION: How do you do this?? The average of the first 3 numbers was 9. The average of the next 7 numbers was 30. What was the overall average of the 10 numbers?

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Question 526363: How do you do this?? The average of the first 3 numbers was 9. The average of the next 7 numbers was 30. What was the overall average of the 10 numbers?
Found 3 solutions by Earlsdon, ankor@dixie-net.com, josmiceli:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
The way you would do this problem is:
Find the sum of the first three numbers (x) then find the sum of the next 7 numbers (y), add these two sums together (x+y) and divide the lot by the total number of numbers, which is 10, (%28x%2By%29%2F10).
x%2F3+=+9 Multiply both sides by 3.
x+=+27
y%2F7+=+30 Multiply both sides by 7.
y+=+210.
%28x%2By%29%2F10+=+237%2F10=23.7


Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
How do you do this?? The average of the first 3 numbers was 9. The average of the next 7 numbers was 30.
What was the overall average of the 10 numbers?
:
Av = %283%289%29+%2B+7%2830%29%29%2F10
:
Av = %2827+%2B+210%29%2F10
:
Av = 237%2F10
Av = 23.7

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
( sum of 1st 3 numbers )/3 = 9
sum of 1st 3 numbers = 27
and
( sum of next 7 numbers ) / 7 = 30
sum of next 7 numbers = 210
---------------------------
sum of all 10 numbers = 27 + 210
sum of all 10 numbers = 237
average of 10 numbers = 237/10
237/10 = 23.7