Question

The average (arithmetic mean) test score for all
the students in a class is 84. The average score
of m boys in the class was 79, while that of
n girls was 87. What is the ratio of m to n?

Answer 1

Answer:

3:5

Explanation:

Total score for the boys is 79×m=79m

Total score for girls is 87×n=87n

Avarage for both is (87n+79m)/(m+n)=84

~

87n+79m=84m+84n

3n=5m

m/n=3/5

3:5

Answer 2

In this exercise we have to use the knowledge of arithmetic mean to calculate the mean of students in a class, so we find:

3:5 students in a class

organizing the information given in the exercise statement we have that:

• Total score for the boys is 79×m=79m
• Total score for girls is 87×n=87n

Calculating this average is:

$(87n+79m)/(m+n)=84\\87n+79m=84m+84n\\3n=5m\\m/n=3/5$

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