Question 3946
The best way is to ratio these problems, let's get started..... 

1 inches : 45 feet = 2.5  (2 1/2) inches : X feet

2.5 times 45 = 112.5 / 1 = 112.5 feet

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10 mins : 3 pcs = X mins : 4 pcs

4 times 10 = 40 / 3 = 13.3 mins.

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7 boys : 8 girls......  total 60 students....

*** Think 30 boys and 30 girls would be a 1 to 1 ratio... but you need a 7 to 8 ratio ****

SO.................

7 X 4 = 28 boy students
8 X 4 = 32 girl students   

28 + 32 = 60 total students 

So..... the answer is 32 girls.

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Good luck!

Carl