Question 1006496: I have 40 questions, 4 marks given for a correct answer, 2 marks deducted for each wrong answer and 1 mark deducted for for each answer not attempted I attempt 19 and score 25 marks.how many questions did I get right?
Answer by Ani_g(8)   (Show Source):
You can put this solution on YOUR website! Let the number of correct answers = x & number of incorrect answers = y
Since I attempted 19 questions, then x + y = 19 ......(1)
For x no. of correct answers I get = 4x
Deduction for y no. of incorrect answers = - 2y
Deduction for (40-19) = 21 non-attempted questions = - 21
Adding these three we get my score, i.e., 25.
Hence, 4x - 2y - 21 = 25
Or, 4x - 2y = 25 +21 = 46
Or, 2(2x - y) = 46
Or, 2x - y = 46/2 = 23 ......(2)
Adding equation (1) & (2) we get,
x + y + 2x - y = 19 +23 = 42
Or, 3x = 42
Or, x = 42/3 = 14
Therefore, I got 14 questions right.
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