Q. 234.3( 12 Votes )

Yash scored

Answer :

To find: Number of questions in a test.


Explanation:


Let the number of right answers be ‘a’ and number of wrong answers be ‘b’


Given, Yash scored 40 marks in a test, getting 3 marks for each right answer and losing 1 mark for each wrong answer.


Deducted marks are represented by "–" sign.


3a b = 40 ……(1)


Had 4 marks been awarded for each correct answer and 2 marks been deducted for each incorrect answer, then Yash would have scored 50 marks


4a 2b = 50 ……(2)


Multiplying eq1 by 2 and subtracting eq2 from it


4a – 2b – 2(3a – b ) = 50 – 2 (40)


4a – 2b – 6a +2b = 50 – 80


4a – 6a = 50 – 80


6a – 4a = 80 – 50


2a = 30


a = 15


Put the value of a in eq. 1 to get,


3(15)–b=40


45 – b = 40


–b=40–45


–b=–5


b=5


Total number of questions in the test = right answers + wrong answers


= 15 + 5


= 20


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