Data Sufficiency

In a class, 20 students speak Spanish, 15 speak French, and 15 speak Chinese. How many students are in the class?

(1) Exactly 30 percent of the students in the class speak French.

(2) All of the students speak English and none speaks more than two languages.


Kaplan's OA: A
My Answer: C



[SPOILERS BELOW]:


Their explanation was:
The stem tells you how many students in a given class speak Spanish, French, and Chinese. You are asked how many students are in the class. You need a relationship between the number of students that speak one of the given languages and the total number of students in the class. Statement (1) gives you this relationship. You know that exactly 30 percent of the students speak French, and you know that 15 students speak French. The percent formula has three terms (percent, part, whole), and you've got two of them (percent and part). Therefore, you can solve for the third part. (1) is sufficient. Statement (2) tells you that all of the students speak English and none speaks more than two languages. However, you don't have any idea how many students in the class speak only English or how many students speak English and a language not mentioned in the question stem, so (2) is insufficient. Choice (A) is the correct answer.


---However, I can't help but think about how many overlapping students there are, i.e.- how many speak (for example) French AND Chinese, for example. The second data point clarifies this point, as we know that there is no overlap between students who speak Spanish, French, and Chinese.

fltingley wrote: ---However, I can't help but think about how many overlapping students there are, i.e.- how many speak (for example) French AND Chinese, for example. The second data point clarifies this point, as we know that there is no overlap between students who speak Spanish, French, and Chinese.

Statement 1: Exactly 30 percent of the students in the class speak French.

From the question stem, we know 15 students speak French. Therefore these 15 students are actually 30% of the class. 70% of the class do not speak French.

we can easily evaluate this:

15/Total = 30%
Total = 50 students.

Sufficient.

Statement 2: All of the students speak English and none speaks more than two languages.

among other things, we don’t know the number of students who only speak 1 language.

Insufficient.

Choose A.

-BM-

But if I go with A, how does that account for the students who may speak French AND Chinese, or Chinese AND something else, etc.?

the question stem and statement 1 no where mentions that they overlap...you are just assuming they do...why would you assume that??

if they overlapped..the question stem would tell you...