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.
(i) Radhika scored 20 marks. If she has got 12 correct answers, how many questions has she attempted incorrectly?
(ii) Mohini scores − 5 marks in this test, though she has got 7 correct answers. How many questions has she attempted incorrectly? [3 MARKS]

Answer 1

Each option:1.5 Marks

As per the question
Marks obtained for 1 right answer = +3
Marks obtained for 1 wrong answer = −2

(i) Marks scored by Radhika = 20

Marks obtained for 12 correct answers = 12 $\times$ 3 = 36

Marks obtained for incorrect answers = Total score − Marks obtained for 12 correct answers
= 20 − 36 = −16

Marks obtained for 1 wrong answer = −2

Thus, number of incorrect answers
= (−16) $÷$ (−2) = 8

Therefore, she had answered 8 questions incorrectly.


(ii) Marks scored by Mohini = −5

Marks obtained for 7 correct answers
= 7 $\times$ 3 = 21

Marks obtained for incorrect answers = Total score − Marks obtained for 12 correct answers
= − 5 − 21 = −26

Marks obtained for 1 wrong answer = −2

Thus, number of incorrect answers
= (−26) $÷$ (−2) = 13

Therefore, she had answered 13 questions incorrectly.