Question

In a test, +3 marks are given for every correct answer and -1 are given for every incorrect answer (i) Sona scored +20 marks though she got 10 correct answers. How many incorrect answers has she attempted??

Answer 1

10 incorrect answers

Explanation:

Correct answer = +3

Incorrect answer = - 1

Mark scored = 20

Number of correct answers = 10

Let:

Incorrect answers = y

Hence, we can fashion out the expression for total score :

(Number of correct answers * score per Correct answer + number of incorrect * score per incorrect) = total score

(10 * 3) + (y * - 1) = 20

30 - y = 20

-y = 20 - 30

-y = - 10

y = 10

10 incorrect answers