a boy gets 3 marks for each correct sum and loses 2 marks for each incorrect sum he does 24 sum and obtains 37 marks the number of correct sums were
Answers
Answer
Don't ask incomplete questions
Step-by-step explanation:
Answer:
No. of correct sums = 17
Step-by-step explanation:
Let
No. of correct sums = x
No. of incorrect sums = y
He does 24 sums in all, hence:
x + y = 24 ..........(i)
Marks earned for each correct sum = 3
=> marks earned for "x" correct sums = 3x
Marks earned for each incorrect sum = -2
=> marks earned for "y" incorrect sums = -2y
(Note: negative marks earned means marks lost)
Total marks earned = 3x - 2y
We are given this to be 37
=> 3x - 2y = 37 ...........(ii)
Multiply (i) by 2
=> 2x + 2y = 48 ..........(iii)
Add (ii) and (iii)
=> 5x = 85
=> x = 17
No. of correct sums = 17
Using (i),
y = 24 - x
y = 24 - 17
y = 7
No. of incorrect sums = 7
Full answer:
No. of correct sums = 17
No. of incorrect sums = 7
Total sums done = 17 + 7 = 24 √
No. of marks earned from correct sums = 17*3 = 51
No. of marks earned for incorrect sums = 7*(-2) = -14
Total marks earned = 51 - 14 = 37 √
Hence, verified.