Question

In an examination consisting of 120 questions, two marks is given for every correct answer and one–third mark is deducted for every wrong attempt. a student attempts all the 120 questions and scores a total of 142 marks. find the number of questions he marked wrong.

Answer 1

let the no of questions marked wrong be x
no of questions marked correct=120-x
2(120-x)-x/3=142
6(120-x)-x=426
720-6x=426+x
720-426=7x
x=294/7
x=42

Answer 2

There are 120 questions in the examination
the student's marks = 142
Marks given for every correct answer= 2
Marks given for every wrong answer = 1/3

By problem,
142/2= 71
which means that 71 questions are correct among all the 120 questions given in the exam.

Remains questions that were considered as mistake = 120-71 = 49
therefore the wrong answers are 49

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