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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?

Name: 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?
Uploaded: 2020-05-04T13:02:31Z
Duration: 5 min 21 s
Description: 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) If Radhika scored 20 marks and she has got 12 correct answers, she attempted 8 incorrect questions, ii) Mohini scores –5 marks in this test, though she has got 7 correct answers, she attempted 13 incorrect questions.

Solution:

(i) Marks given for every correct answer = 3 marks

Marks given for every incorrect answer = -2

Marks for not attempting any question = 0

The total score of Radhika = 20 marks

Number of correct answers given by Radhika = 12 answers

Marks obtained for correct answers = 3 × 12 = 36 marks

Marks obtained for incorrect answers = Total score - Marks obtained for 12 correct answers

= 20 - 36 = -16 marks

Marks obtained for every incorrect answer = -2 marks

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

Therefore, she attempted 8 incorrect questions.

(ii) Total score of Mohini = -5

Number of correct answers given by Mohini = 7

Marks obtained for correct answers = 7 × 3 = 21 marks

Marks obtained for incorrect answers = Total score - marks obtained for correct answers

= - 5 - 21

= - 26

Marks obtained for every incorrect answer = -2 marks

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

Therefore, she attempted 13 incorrect questions.

☛ Check: NCERT Solutions for Class 7 Maths Chapter 1

Video Solution:

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?

NCERT Solutions Class 7 Maths Chapter 1 Exercise 1.4 Question 6

Summary:

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) If Radhika scored 20 marks and she has got 12 correct answers, she attempted 8 incorrect questions, ii) Mohini scores –5 marks in this test, though she has got 7 correct answers, she attempted 13 incorrect questions.

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