test scores

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test scores

by grandh01 » Fri Aug 03, 2012 5:07 pm
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
Source: — Problem Solving |

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by eagleeye » Fri Aug 03, 2012 5:11 pm
grandh01 wrote: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
Lets say student answered x questions correctly.
Incorrect answers = 50-x.
Marks for correct questions = x*1 = x
Marks for incorrect questions = -2*(50-x) = 2x-100
Total marks = 38 = x +2x-100 => 3x = 138 => x = 138/3 = 46 :)
E is correct.

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by Anurag@Gurome » Fri Aug 03, 2012 6:25 pm
grandh01 wrote: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
Let us assume that the student answered C questions correctly.
Then Wrong = W = 50 - C
So, 38 = C - 2W
38 = C - 2(50 - C)
3C - 100 = 38
C = 46

The correct answer is E.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

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