Question 761524


The student needs to maintain an average of 81 in 2 tests.

By definition, average of n items is the sum of the n numbers divided by n.

Average = sum of scores in 2 tests / 2  

{{{81 = Sum / 2}}}

So the student needs to score a total of {{{81 * 2 = 162}}} in the 2 tests.

He has already scored 72 in the 1st test.

How much should he score in the 2nd test? Just subtract from the total (162 - 72), to get 90.

So he should score 90 in the second test to get an average of 81.


(Check out problem number 761220 also, to understand how averages work.)

:)