A student answered 40% of the firt 30 questions on a test

Question

A student answered 40% of the firt 30 questions on a test. Assuming he answers all the remaining questions correctly how many correct answers did he answer.

i) the total number of correct answers was 80%
ii) the total number of questions in the exam were 90.

I hate these badly worded problems..aaaggggh!

Vijo · Answer

A student answered 40% of the firt 30 questions on a test.  Assuming he answers all the remaining questions correctly  how many correct answers did he answer.

i) the total number of correct answers was 80%
ii) the total number of questions in the exam were 90.


I hate these badly worded problems..aaaggggh


remaining of those 30 questions or reminaing of the total???????????

banerjeea_98 · Answer

"D". 

I think the stem shud be:

A student answered 40% of the firt 30 questions on a test  correctly .

Say we have X total ques

I. Total correct: 12 + X-30 = X*80/100.....X = 90.....so we know the correct ans

II. If we know the total we know the correct ans.....12 + 60 = 72 i.e. also 80% correct.

FN · Answer

well why are u assuming that the student answered correctly, maybe he answered some incorrect and missed the rest??

Marina · Answer

A student answered 40% of the first 30 questions, and all other questions answered correctly.
Each statement is sufficient, thus D

Folaa3 · Answer

If he answered some incorrect and missed the rest, then the answer is (E)

HongHu · Answer

The stem says that he answered all the remaining questions correctly.

greenandwise · Answer

My answer is C...I think this is supposed to be the trick. The information in the questions seems irrelavent. Because it says only that he answered 40% of the first 30 questions. Since it does not say that he answered 40% of them correctly then we can use A and B to come up with the toltal he got right...the OA would aleve all doubt though.

HongHu · Answer

Oh! I see your point. You're right in the case.

I highly doubt that ETS would write questions like this just to trick us though. I think it is a badly worded question.

greenandwise · Answer

HongHu are you serious?! :lol:

That's all they spend their time doing!

Folaa3 · Answer

Freshinha12, what is the source of this question please? I doubt (just like HongHu said) the ETS will poorly word a question like this and expect people to fill in the blanks unless it's an experiment question. 

The stem does not say if 40% of the first 30 questions were correctly answered. That is the only basis on which D will be the answer

HongHu · Answer

My judgement is backed with the OA. :-D

Ok seriously I agree that they would try to set up all kind of traps for us. But from my own experiences, all of their traps are clearly set, even if they are very easy to be overlooked. Whereas this question is simply badly worded and open to explanation.

cloaked_vessel · Answer

A student answered 40% of the firt 30 questions on a test. Assuming he answers all the remaining questions correctly how many correct answers did he answer. 

i) the total number of correct answers was 80% 
ii) the total number of questions in the exam were 90. 

I think the answer should be A

Why 1 is Sufficient.

Let x be the additional questions, so we have a total of 30+x questions:

For the first 30, we have:
.4*30= 12 Answered
18 Unanswered (Wrong)

Let a be the amount of questions incorrect on the 12 answered. Then 12-a is the amount of correct answers.

From Stem1:
Correct =4/5 ; Incorrect(Unanswered)=1/5

.2 = (18+a)/(30+x)
.8 = (12-a+x)/(30+x)

Two equations, two unknowns, we can compute the total number of correct questions.

From Stem2:
90 Questions:

For the first 30, we have:
.4*30= 12 Answered
18 Unanswered (Wrong)


Let a be the amount of questions incorrect on the 12 answered. Then 12-a is the amount of correct answers.

Total Correct = 12-a+60
Total Incorrect = a+18
Total Questions = 90.

I don't think we can determine the value for "a" based on the fact that there are only 90 questions without any indications to the amount of correct/incorrect.


Can someone explain how the OA is D? Is there a typo on the question text perhaps?

Thanks,

HongHu · Answer

We are assuming that the 12 questions he answered are correct answers. Then we can get (D).

If you are assuming that you don't know how many of the 12 he answered right, then you should get (E). (I) is not sufficient. The two equations of yours is essentially the same. Try solve it you'll know what I mean.

A student answered 40% of the firt 30 questions on a test

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