Problema Solution
Katie's math teacher gave 20 four-question quizzes. Katie remembered she scored either 75% or 100% on all of the quizzes. If her average quiz grade is 90%, how many of each score did she earn?
Answer provided by our tutors
If she scored 100% on x quizzes, then
100x + 75 (20-x) = 90*20
or, 100x + 1500 - 75x = 1800
or, 25x = 300
so, x= 12
So, she scored 100% on 12 quizzes and 75% in 8 quizzes