Question

3. There are 100 multiple choice questions in an examination. For every correct answer the student gets 5marks and for every wrong answer 2 marks are deducted from the total score of correct answers. Suppose, the student attempts all the questions and his total score is 220,how many questions did he attempt correctly?

Answer 1

Answer:

Step-by-step explanation:

let X be no.of correct answers

let y be no.of wrong answers

therefore X+y=100. equation 1

and. 5x-2y=220 equation 2

by substitution method

X=100-y

putting value of X in equation 2

5(100-y)-2y=220

500-5y-2y=220

-7y=220-500

y=-280/-7

y=40

therefore putting value of y

X=100-40

X=60

therefore he attempted 60 questions correctly