Question

1. In a test +4 marks are given for every correct answer and –2 for every incorrect answer.
a) Niharika answered all the questions and scored 20 marks though she got 10 correct answers.
Find the number of incorrect answers

Answer 1

Let the incorrect answers be X.

4*10 - 2*X = 20

40 - 2X = 20

-2X. = -20

X = 10 Ans.

Answer 2

It is given that,for every right answer 4 marks are awarded and for every wrong answer 2 marks are deducted.

So for 10 right answers Niharika will get 40 marks but she got 20 marks as her total.
So, she lost 20 marks for wrong answers(40-20=20).
To find the number of wrong answers we should divide number of marks lost in writing wrong answers by number. of marks deducted for each wrong answer.
We will thus get 20/2=10.

So she wrote 10 incorrect answers.