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?

Solution

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

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

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