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In a class of 30 students, 17 students study Chinese, and r

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aliensoybean
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In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   18 Nov 2007, 22:13
In a class of 30 students, 17 students study Chinese, and r students study japanese. Every student studies either Chinese, Japanese, or both. How many students study both Chinese and Japanese?

1. r = 14
2. 13 students take only Japanese

Why is the answer 1 only? I think 2 is okay well because:
we know from opening statement that, 30=17+r-both
Statement two tells us that 30=17+13-both. In this case, both equals 0

What am I missing? THANKS!



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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   18 Nov 2007, 22:27
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:?
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   19 Nov 2007, 12:42
aliensoybean wrote:
In a class of 30 students, 17 students study Chinese, and r students study japanese. Every student studies either Chinese, Japanese, or both. How many students study both Chinese and Japanese?

1. r = 14
2. 13 students take only Japanese

Why is the answer 1 only? I think 2 is okay well because:
we know from opening statement that, 30=17+r-both
Statement two tells us that 30=17+13-both. In this case, both equals 0

What am I missing? THANKS!


You are looking at #2 wrong.
For #2, ONLY Japaneses means this:
r-both = 13

r is defined as ALL Japaneses students, not ONLY Japanese students
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   19 Nov 2007, 13:52
Total = Set1 + Set2 + Neither - Both

30 = 17 + r + 0 - Both

statement 1

r = 14

30 = 17 + 14 + 0 - Both

Both = 1

sufficient

statement 2

insufficient

Both = r - 13 ?

the answer is (A)
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   19 Nov 2007, 14:06
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I cry :cry:
#2 insufficient means a few cases. It is clearly for me that 13+17 is good and is single case..... :(
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   19 Nov 2007, 21:47
The second statement basically gives you this equation.

Only Chinese + (both chinese and japanese) = 17.

Therefore, statement 2 is insufficient.
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   19 Nov 2007, 22:42
aliensoybean wrote:
In a class of 30 students, 17 students study Chinese, and r students study japanese. Every student studies either Chinese, Japanese, or both. How many students study both Chinese and Japanese?

1. r = 14
2. 13 students take only Japanese

Why is the answer 1 only? I think 2 is okay well because:
we know from opening statement that, 30=17+r-both
Statement two tells us that 30=17+13-both. In this case, both equals 0

What am I missing? THANKS!


Both does not equal 0. Neither equals 0. Both = r-13.
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   20 Nov 2007, 22:37
makes sense, thanks a lot guys!
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink] New post   22 Nov 2007, 05:54
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:roll: thanks!



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
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Re: In a class of 30 students, 17 students study Chinese, and r [#permalink]
22 Nov 2007, 05:54
Moderator:
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3137 posts

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