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# The current ratio of boys to girls at a certain school is 2 to 5. If 1

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Re: The current ratio of boys to girls at a certain school is 2 to 5. If 1 [#permalink]
I have another approach:
B:G= 2:5
(B+12):G=4:9 --> (B/G) + (12/G) = 4/9
(2/5) + (12/G) = 4/9 -->(2G +60)/5G= (4/9) (I replace B/G by the ratio 2/5)-->G=270
(B/G)= (2/5) (replace G=270)-->B=108

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Re: The current ratio of boys to girls at a certain school is 2 to 5. If 1 [#permalink]
Bunuel wrote:
The current ratio of boys to girls at a certain school is 2 to 5. If 12 additional boys were added to the school, the new ratio of boys to girls would be 4 to 9. How many boys currently attend the school?

(A) 27
(B) 48
(C) 54
(D) 72
(E) 108

$$\frac{2x + 12}{5x} = \frac{4}{9}$$

Or, $$18x + 108 = 20x$$

Or, $$2x = 108$$

Or, $$x = 54$$

So, The total number of boys is $$2*54 = 108$$ , Answer must be (E)
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Re: The current ratio of boys to girls at a certain school is 2 to 5. If 1 [#permalink]
Bunuel wrote:
The current ratio of boys to girls at a certain school is 2 to 5. If 12 additional boys were added to the school, the new ratio of boys to girls would be 4 to 9. How many boys currently attend the school?

(A) 27
(B) 48
(C) 54
(D) 72
(E) 108

b/g=2/5→
4g=10b, equation 1
(b+12)/g=4/9→
4g=9b+108, equation 2
subtracting 2 from 1,
b=108
E
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Re: The current ratio of boys to girls at a certain school is 2 to 5. If 1 [#permalink]
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Re: The current ratio of boys to girls at a certain school is 2 to 5. If 1 [#permalink]
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