Question

There are 100 multiple choice questions in an examination.for every correct answer the student gets 5 marks 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

Let x be correct and y be incorrect question
x+y = total
x+y = 100
1 correct = 5 marks
x correct = 5x
1 incorrect = 2 marks
y incorrect = 2y marks
total marks obtained
5x-2y = 220
x+y =100
y = 100-x
5x-2(100-x) =220
5x-200+2x= 220
7x= 420
x = 60
Number of correct questions attempted = 60