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500 ds

by dunkin77 » Tue Apr 03, 2007 9:37 pm
Hi,

I thought the answer was D) by 50 - 2inc = 38 inc=6 therefore 50-6=44 but turned out the answer is E)...can anyone help?

An instructor scored a student’s test of 50 questions by subtracting 2 times the number of incorrect answers from the number of correct answers. If the student answered all of the questions and received a score of 38, how many questions did that student answer correctly?
(A) 19
(B) 38
(C) 41
(D) 44
(E) 46
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by jayhawk2001 » Tue Apr 03, 2007 9:43 pm
Let c and i be the number of correct and incorrect questions resp.

We have 2 equations --

c - 2i = 38
c + i = 50

Solving for c, we get 46. Hence E
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Re: 500 ds

by ajith » Tue Apr 03, 2007 9:43 pm
dunkin77 wrote:Hi,
I thought the answer was D) by 50 - 2inc = 38 inc=6 therefore 50-6=44 but turned out the answer is E)...can anyone help?
The problem lies in the underlined part,
The total marks = Number of Correct answers - 2* Incorrect answers
(no of correct answers is not 50 it is 50-inc)

now,

50-inc-2*inc=38
=> inc =4

that leaves 46 as the answer
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by dunkin77 » Tue Apr 03, 2007 9:53 pm
oh! I seee.... Thank you!
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by Cybermusings » Wed Apr 04, 2007 3:09 am
Let total number of incorrect answers be x. Thus the teacher substracted 2x from the number of correct answers (number of correct answers would obviously be equal to 50 - x)

50 - x - 2x = 38

12 = 3x

x = 4. Hence correct answers = 50-4 = 46
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