Radhika scored 20 marks. if she has got 12 correct answers, how many questions has she attempted incorrectly?

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?

Answer 1

i) Let the no. of incorrect answers = x 

So score = 3 × No. of correct answers + (-2) No. of incorrect answers 

Radhika score = 20 marks 

⇒ 20 = 3 × 12 + (-2) x 

⇒ 20 = 36 – 2x 

⇒ 2x = 36 – 20 

⇒ x = 16/2 = 8 

∴ No. of incorrect questions = 8

ii) Mohini scores = -5 

Marks for correct answers = 7 × 3 = 21 

Marks for incorrect answers = -5-21 = -26 

∴ Number of incorrect answers = -26 ÷ 2 = -13