Question 972175
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The average of the first three numbers is 80, so the total sum of the numbers is (3 x 80) 240.
For the next 9 numbers, the sum would be (9 x 40) 360.
The sum of the 12 (9+3) numbers would be (240+360) 600.
The average of 12 numbers whose sum is 600 is (600/12) 50.
ANSWER: The overall average of the numbers is 50.