Brooke has scores of 84, 72, 90, 95, and 87 on her first five quizzes. after taking the sixth quiz, brooke’s mean score increased.

the complete question is
Brooke has scores of 84, 72, 90, 95, and 87 on her first five quizzes. After taking the sixth quiz, Brooke’s mean score increased. 
Which could be Brooke’s sixth quiz score? Check all that apply.
85
90
83
86
92
89

step 1
Find the mean
To do this, add all the numbers, then divide by the number of numbers there are.
so


step 2
if after taking the sixth quiz, Brooke’s mean score increased
then
the sixth score of Brooke's quiz must be higher than the mean obtained in the first 5 quizzes

case a)
------> is not a solution

case b)
------> is a solution

case c)
------> is not a solution

case d)
------> is a solution

case e)
------> is a solution

case f)
------> is a solution

the answers are