Question

In a class test (+3) marks are given for every correct answer and (–2) marks are given for every incorrect answer and no marks for not attempting any question. Mohini scores –5 marks in this test, though she has got 7 correct answers. How many questions has she attempted incorrectly?

Answer 1

Marks scored for 1 correct answer = +3

Marks scored for 1 incorrect answer = −2

Marks scored by Mohini = −5

Marks scored for 7 correct answers = 7 × 3 = 21

Marks scored for incorrect answers = Total marks scored − Marks scored for 7 correct answers

= − 5 − 21

= −26

Marks scored for 1 incorrect answer = −2

Thus, number of incorrect answers = (−26) ÷ (−2)

= 13

Therefore, she attempted 13 questions incorrectly.