Question

Q1.In a test, 10 marks are given for each correct answer and -2 marks are given for each wrong answer. Jaswinder scored 90 marks, answering 10 questions correctly. How many questions did he answer incorrectly?
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Answer 1

Let the number of correct answers be x

Number of wrong answers be y

According to question , 10 marks are given for each correct answer and -2 marks are given for each wrong answer.

1 correct answer = 10 marks

x correct answers = 10 × x

= 10x

1 wrong answer = -2 marks

y wrong answers = -2 × y

= -2y

He answered 10 questions correctly

Hence , 1 correct answer = 10 marks

10 correct answers = 10×10

= 100

So, 10x = 100

→ x = 100/10

→ x = 10

Now , Jaswinder scored 90 marks.

Therefore ,

10x + (-2y) = 90

→ 10x - 2y = 90

→ 10×10 - 2y = 90

→ 100 - 2y = 90

→ -2y = 90-100

→ -2y = -10

→ 2y = 10

→ y = 10/2

= 5

The number of incorrect answers is 5.