Wednesday 2 November 2011

Algebra-17 (XAT-2009)

In an examination there are 30 questions. 1 mark is given for each correct answer and 0.25 is deducted for every incorrect answer. Ankur attempted all the questions and scored 13.75.How many incorrect answers did he have?
(1) 10   (2) 11  (3) 12  (4) 15  (5) None of these
For Answer Click on "Read more" below:
Solution:
Observe that it is asked about number of incorrect answers.
Let the number of incorrect answers be ‘x’ => number of correct answers = 30-x
“1 mark is given for each correct answer and 0.25 is deducted for every incorrect answer”
=> total marks scored by Ankur =
(30-x)*1 - x*(0.25) = 13.75
Multiplying with 4 on both sides:
=> 120-4x-x =55 => 5x = 65 => x = 13
Answer (5)

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