Question 983622
Ella’s test grades in her history class are 89, 94, 82, 84, and 98. What score must Ella make on her next test to have a mean test score of 90?

Solution:
Let x = Ella's last score
We want {{{(89+94+82+84+98+x)/6 = 90}}}
Multiply both sides by 6
89 + 94 + 82 + 84 + 98 + x = 540
447 + x = 540
x = 93
Answer: {{{highlight(93)}}}