Question 1208136
<br>
By the basic method, using the definition of average directly....<br>
{{{(85+79+92+100)/4=356/4=89}}}<br>
ANSWER: 89<br>
Or by a method which is sometimes easier in cases where all the numbers are "close together"....<br>
(1) Using a quick examination of the given numbers, make a guess for the average.  In this example, 90 should be close.<br>
(2) Determine, for each given number, the "over" or "under" compared to your guess for the average; then find the total over or under.
85: -5
79: -11
92: +2
100: +10
total: -16+12 = -4<br>
(3) Divide the total over or under by the number of quiz scores to find the average over or under
-4/4 = -1<br>
Adjust your guess by that average over or under to get the actual average
90+(-1) = 89<br>
ANSWER (again, of course): 89<br>