Question 1095098
<br>Josgarithmetic said get a second opinion....  Her answer is fine; but I would solve the problem differently....<br>
If we are looking for the minimum average of the other 8 students, then we want the 4 students who got A's to get the highest possible score, which I will assume is 100.<br>
Let's talk scores out of 100 instead of percentages, to make the description easier....<br>
The average is 80, and 4 students each scored 100.  That is a total of 4*20=80 points above what is needed to make an average of 80.  That means the average for the other 8 students must be such that their total scores are 80 below the overall average of 80.  80 points, divided equally among the 8 students, is 10 points each.  So the average of the other 8 students is 10 points below the overall average of 80; 80-10 = 70.