Problema Solution
Fred scored a 60, 70, then 75 on his first three tests. How many tests must he score a 90 on in order to have an overall score of 80?
Answer provided by our tutors
Let x represent the number of tests that Fred must score a 90
(60 + 70 + 75 + 90x)/(x + 3) = 80
........
........
x = 3.5 test
We got a solution that is not integer, thus it is not possible under this conditions for Fred to have an average of 80.