Question 666442
Use A = sum/6 = 90
The sum of first 5 is 5*88.
Let x = score required on sixth test.
The new sum will be 5*88 + x
The new average is new sum divided by or
(1) 90 = (5*88+x)/6 or
(2) 540 = 5*88 + x or
(3) x = 540 - 440
(4) x = 100
Answer: Maria must get 100 on the sixth exam to obtain a 90 average.
I feel bad for Maria, but at least she don't need more than 100!