Question

In a true-false test containing 50 questions, a student is to be awarded 2 marks for every correct answer and -2 for every incorrect answer and 0 for not supplying any answer. If Yash scored 94 marks in a test, what are the possibilities of his marking correct or wrong answer

Answer 1

1. 47 correct, 0 wrong and 3 unanswered

2. 48 correct, 1 wrong and 1 unanswered

Explanation:

Given;

Total number of questions = 50

For correct answers = 2

For wrong answers = -2

Unanswered questions = 0

Yash scored 94 marks

Let c, w and u represent the number of correct, wrong and unanswered questions

2×c - 2 × w + 0×u = 94

2c -2w = 94 .....1

And;

c + w + u = 50 .....2

We have 2 equations and 3 unknowns

By observing the problem, we can see two possible solutions;

Case 1: Assuming he did not miss (get wrong) any answer;

He needs to score 47 answers right;

47 × 2 = 94

Then;

c = 47 w = 0 and u = 50 - (47+0) = 3

47 correct, 0 wrong and 3 unanswered

Case 2: Assuming he got one answer wrong;

He would need to score one more answer right compared to the first case;

(47+1) × 2 - 1 × 2 = 96 - 2 = 94

c = 47+1 = 48

w = 1

u = 50 - (48+1) = 1

So he need to score 48 correct answers, 1 wrong answer and 1 unanswered.