SOLUTION: An eighth grade class picnic has a boy-girl ratio of 5:3. Three more girls join the class, changing the ratio to 10:7. How many students are now in the class?

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Question 220194: An eighth grade class picnic has a boy-girl ratio of 5:3. Three more girls join the class, changing the ratio to 10:7. How many students are now in the class?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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An eighth grade class picnic has a boy-girl ratio of 5:3.
Three more girls join the class, changing the ratio to 10:7. How many students are now in the class?
:
Let m = the multiplier
:
%285m%29%2F%283m%2B3%29 = %2810%29%2F%287%29
Cross multiply
7(5m) = 10(3m+3)
35m = 30m + 30
35m - 30m = 30
5m = 30
m = 30%2F5
m = 6 is the multiplier
:
Find the no. of girls now
girls = 3(6) + 3
girls = 21 girls
:
:
Check solution
6*5 = 30 boys
:
30/21 = 10/7