Question

a boys get 3 marks correct sum losses 2 to each incorrect sum he does 24 sum obtained 37 marks find the number of correct sum?

Answer 1

let the correct sum be X
since total attempted question = 24
thus incorrect = 24-x
he gets 3 marks for correct
-2 for incorrect
thus
3(X) -2(24-x) = 37
3x-48+2x = 37
5x = 85
X = 17

Answer 2

The number of correct sum is 17

Explanation:

Given :

1. A boys get 3 marks correct sum

2. Losses 2 to each incorrect sum

3. He does 24 sum obtained 37 marks

To find:

Find the number of correct sum

Let,

Correct sum = x

Incorrect sum =y

==> He does 24 sum which has both correct and incorrect question.

==> x+y=24 ==>1

==> Marks for correct question is 3

==> Marks for incorrect question is -2

==> Total mark obtained is 37

==> Write equation as the condition given

==>  3x-2y=37 ==>2

Solving, equation 1 and 2

==>  x + y =24

==> 3x - 2y=37

Solving these equation by elimination method.

Equation 1 can written as

==> 3x+3y = 72===> 3

Solving equation 3 and 2

==>3x+3y = 72

==>3x - 2y=37(changing sign)

    ------------------

      0 +5y=35

    ------------------

==>5y = 35

==>y = 35/5

==>y= 7

Substitute y value in equation 1

==> x+y=24

==> x+7=24

==> x=24-7

==> x=17

17 question he attended were correct

7 question he attended were Incorrect

Check whether the answer is correct or not

17×3 = 51

7×2= 14

==> 51-14=37

The answer is correct