Question 1113586
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To have a chance of solving the problem, we have to assume (since it is not stated) that all tests have the same weight.<br>
But when we do that, the numbers given in the problem don't allow us to find a solution.<br>
If the average on the first n tests is 84 and the next test is 93, then the sum of all the test scores is 84n+93; if the average after that last test is 86, then the sum of all the test scores is 86(n+1).<br>
But solving the equation 84n+93 = 86(n+1) to find the original number of tests does not give an answer that is a whole number.  Obviously the number of tests must be a whole number -- so the problem as stated can't be solved.