Answer
Find out the weighted mean .
To prove
As given
Elaine gets quiz grades of 71, 75, and 64.
She gets a 60 on her final exam
if the quizzes each count for 20% and the final exam counts for 40% of the final grade.
20 % is written in the decimal form
[tex]= \frac{20}{100}[/tex]
= 0.20
40 % is written in the decimal form
[tex]= \frac{40}{100}[/tex]
= 0.40
20% of 71 =  0.20 × 71
        = 14.2
20% of 75 =  0.20 × 75
         = 15
20% of 64 =  0.20 × 64
         = 12.8
40% of 60  = 0.40 × 60
         = 24
Thus
Weighted mean = 14.2 + 15 + 12.8 + 24
              = 66
