In Mr. Smith's class, what is the ratio of the number of boy : GMAT Data Sufficiency (DS)
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# In Mr. Smith's class, what is the ratio of the number of boy

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In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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20 Aug 2012, 02:20
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In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

(1) There are 3 times as many girls as boys in Mr. Smith's class.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class.

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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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20 Aug 2012, 02:20
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SOLUTION

In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

We find the value of $$\frac{B}{G}$$.

(1) There are 3 times as many girls as boys in Mr. Smith's class --> $$G=3B$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class --> $$B=\frac{1}{4}(B+G)$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.

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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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20 Aug 2012, 09:56
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The Answer is (D), each statement alone is sufficient.

We are searching for $$\frac{Boys}{Girls}= ?$$

Statement 1: "(1) There are 3 times as many girls as boys in Mr. Smith's class."

So we have $$3B = G$$. $$\frac{B}{3B}=\frac{1}{3}$$. Sufficient.

Statement 2: "(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class."

So we have $$1/4(G+B) = B => 1/4G + 1/4B = B => 1/4G = 3/4B => G = 3B.$$

$$\frac{B}{3B}=1/3$$. Sufficient.
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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24 Aug 2012, 06:04
SOLUTION

In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

We find the value of $$\frac{B}{G}$$.

(1) There are 3 times as many girls as boys in Mr. Smith's class --> $$G=3B$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class --> $$B=\frac{1}{4}(B+G)$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.

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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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08 Oct 2014, 08:42
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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30 Jul 2016, 07:53
Bunuel wrote:
In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

(1) There are 3 times as many girls as boys in Mr. Smith's class.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class.

We need to determine the ratio of the number of boys to the number of girls. If we denote the number of boys as b and the number of girls as d, we can say:

b/g = ?

Statement One Alone:

There are 3 times as many girls as boys in Mr. Smith's class.

Using statement two we can say:

g = 3b

g/b = 3

b/g = 1/3

Statement one is sufficient to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone:

The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class.

Using statement two we can say:

b = ¼(b + g)

4b = b + g

3b = g

b/g = 1/3

Statement two is sufficient to answer the question.

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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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27 Jan 2017, 11:52
ScottTargetTestPrep wrote:
Bunuel wrote:
In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

(1) There are 3 times as many girls as boys in Mr. Smith's class.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class.

We need to determine the ratio of the number of boys to the number of girls. If we denote the number of boys as b and the number of girls as d, we can say:

b/g = ?

Statement One Alone:

There are 3 times as many girls as boys in Mr. Smith's class.

Using statement two we can say:

g = 3b

g/b = 3

b/g = 1/3

Statement one is sufficient to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone:

The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class.

Using statement two we can say:

b = ¼(b + g)

4b = b + g

3b = g

b/g = 1/3

Statement two is sufficient to answer the question.

Sir, Please help me with the translation There are 3 times as many girls as boys. I always get it wrong.
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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29 Jan 2017, 00:29
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rajatbanik, this is an idiom that many people struggle with. The first quantity named will always be the larger one. So if I say "There are three times as many girls as boys," then there are more girls. If I say "there are twice as many apples as bananas," then there are more apples.

To turn this into an equation, put the quantities on either side of the equal sign before deciding where to attach numbers:

g = b a = b

If you go in the stated order, the first quantity will be larger. So, to make the two equations equal, you need to multiply the smaller quantity by the stated amount.

g = 3b a = 2b

Now the equations fit the statements. There are three times as many girls as boys, so we need to triple the boys to make the quantities equal. There are twice as many apples as bananas, so we need to double the bananas to make them equal.

Notice that the sides get flipped if we use a fraction less than 1. For instance, the statement "There are 1/3 as many cars as bicycles" means that there are fewer cars. Now the first quantity in our equation is smaller:

c = b

To make the two sides equal, we need to attach 1/3 to the larger quantity

c = 1/3 b

There are 1/3 as many cars as bicycles, so only 1/3 of the bicycles would equal the number of cars.

I hope this helped. Let me know if I can clarify.
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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29 Jan 2017, 02:47
[quote="DmitryFarber"]

Thank you DmitryFarber.
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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13 Feb 2017, 23:55
Bunuel wrote:
SOLUTION

In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

We find the value of $$\frac{B}{G}$$.

(1) There are 3 times as many girls as boys in Mr. Smith's class --> $$G=3B$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class --> $$B=\frac{1}{4}(B+G)$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.

Are you sure that this is a 600 Problem? It looks very easy
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Re: In Mr. Smith's class, what is the ratio of the number of boy [#permalink]

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14 Feb 2017, 00:30
ion wrote:
Bunuel wrote:
SOLUTION

In Mr. Smith's class, what is the ratio of the number of boys to the number of girls?

We find the value of $$\frac{B}{G}$$.

(1) There are 3 times as many girls as boys in Mr. Smith's class --> $$G=3B$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.
(2) The number of boys is 1/4 of the total number of boys and girls in Mr. Smith's class --> $$B=\frac{1}{4}(B+G)$$ --> $$\frac{B}{G}=\frac{1}{3}$$. Sufficient.

Are you sure that this is a 600 Problem? It looks very easy

The difficulty level is calculated automatically based on the timer stats from the users which attempted the question. So, yes it is a 600-level question.
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Re: In Mr. Smith's class, what is the ratio of the number of boy   [#permalink] 14 Feb 2017, 00:30
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