Question 1190923
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In a problem about averages where all the numbers are close together, you can often find the answer quickly by using an "over and under" analysis.<br>
In this case, if the average on the first 3 tests had also been 84, then the average on all 8 tests would be 84.
However, he scored an average of 3 points above 84 on those first 3 tests.  That's a total "over" of 4*3=12 points.
12 "over" points averaged over the 8 tests is an average "over" of 12/8=1.5.
So his average is 84+1.5=85.5.<br>