Question

Std 9th Algebra practice set 5.2
in a competitive examination there were 60 questions. The correct answer would carry 2 marks and for incorrect answer 1 mark would be subtracted. Yashwant had attempted all the questions and he got total 90 marks . Then how many questions he got wrong?

Answer 1

therefore the answer is 10 questions by solving this in the picture

Answer 2

Answer:

10

Step-by-step explanation:

Let  x be the number of correct answers

Let y be the number of incorrect answers

He attempted all questions.

Total no. of questions = 60

So, $x+y=60$  --A

Number for 1 correct answer = 2

So, number for x correct answers = 2x

Number for 1 incorrect answer = -1

So, number for y incorrect answers = -y

He got marks = 90

So, equation becomes : $2x-y=90$  --B

Add A and B

$x+y+2x-y=60+90$

$3x=150$

$x=50$

So, Number of correct answers = 50

Substitute the value of x in A

$50+y=60$

$y=60-50$

$y=10$

So, number of wrong answers is 10

Hence he got 10 wrong answers.