Question

in a class test containing 30 questions, 4 marks are giving for every correct answer, and (-2) marks are giving for every incorrect answer. jay attempts all questions and 16 of his answers are correct. what is his total score?

Answer 1

Answer:

Step-by-step explanation:

Here, we are given positive marks every correct answer and negative marks for every incorrect answer i.e. for the correct answer =+5 and for every incorrect answer =−2 marks.

Case1: Radhika got total marks =30 , correct answer =10

So, the total marks for correct answer = marks for correct answer × number of correct answers.

Total marks for correct answer =5×10=50

Thus, Radhika got a total 50 marks for 10 correct answers.

Now, subtracting total marks she got from total marks of correct answer we will get marks for incorrect answer. So, writing as

=50−30=20 marks.

So, she got 20 marks for the incorrect answer. Now, we know that for every incorrect answer =−2 marks.

So, the total marks for incorrect answer = marks for incorrect answer × number of incorrect answers

Substituting values, we get

20=−2× number of incorrect answers

So, dividing by −2 on both sides, we get

Number of incorrect answers =−10

So, the number of incorrect answers are 10 (we can ignore minus sign here because the question cannot be in negative value).

Case2: Jay got total marks =−12 , correct answer =4

So, the total marks for correct answer = marks for correct answer × number of correct answers.

Total marks for correct answer =5×4=20

Thus, Jay got a total 20 marks for 4 correct answers.

Now, subtracting total marks he got from total marks of correct answer we will get marks for incorrect answer. So, writing as

=20−(−12)=20+12=32 marks.

So, he got 32 marks for incorrect answers. Now, we know that for every incorrect answer =−2 marks.

So, the total marks for incorrect answer = marks for incorrect answer × number of incorrect answers

Substituting values, we get

32=−2× number of incorrect answers

So, dividing by −2 on both sides, we get

Number of incorrect answers =−16

So, the number of incorrect answers are 16 (we can ignore minus sign here because the question cannot be in negative value).

Hence, Radhika and Jay got 10 and 16 questions incorrect, respectively.