6. 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?

Answers (1)
H Harsh Kankaria

Given,

Marks for every correct answer = +3

Marks for every wrong answer = - 2

(i) According to question,

Marks obtained by Radhika = 20

Number of correct answers = 12

\therefore Marks obtained for correct answers = 12\times3 = 36

\therefore Marks obtained for incorrect answers = Total marks – Marks obtained for correct answers

\\ = 20 - 36 \\= - 16

\therefore Number of incorrect answers = (-16)\div (-2)

\\ = \frac{16}{2} \\ = 8

Therefore, Radhika attempted 8 questions incorrectly.

(ii) 

According to question,

Marks obtained by Mohini = -5

Number of correct answers = 7

\therefore Marks obtained for correct answers = 7\times3 = 21

\therefore Marks obtained for incorrect answers = Total marks – Marks obtained for correct answers

\\ = (-5) - 21 \\= - 26

\therefore Number of incorrect answers = (-26)\div (-2)

\\ = \frac{26}{2} \\ = 13

Therefore, Mohini attempted 13 questions incorrectly.

 

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