Ratio Problem

Algebra Level 2

Students in a class are divided into two groups, group A and group B. The average mark of group A is 6.7 6.7 and group B is 7.5 7.5 . If the average mark in the class is 6.9 6.9 , then the ratio of students in group A and group B is . . . .

1 : 3 1 : 3 3 : 2 3 : 2 1 : 2 1 : 2 3 : 1 3 : 1

Nicholas Vincent by Nicholas Vincent , 25, Indonesia

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2 solutions

Caleb Townsend
Feb 28, 2015

The differences between the averages are 0.2 0.2 and 0.6 , 0.6, from A A and B B respectively. The ratio of group sizes is the same as the ratio of differences of the average, so A B = 0.6 0.2 = 3 \frac{A}{B} = \frac{0.6}{0.2} = \boxed{3}

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Akshay Ramen
Oct 31, 2015

(.75)/(.25)=3

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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