Question

Yash scored 40 marks in an test getting 3 marks for each right answer and losing 1 mark for each wrong answer. 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. how many questions were there in the test? solve by cross multiplication method

Answer 1

question seems incorrect pls check and edit the question and I will edit my answer after it

Answer 2

Answer:

Step-by-step explanation:

let the number of right answers be "x"

and the number of wrong answers be "y"

now, 1st case

marks got for each right answer = 3

marks deducted for each wrong answer= 1

therefore, 3x - 1y = 40

=> 3x - y = 40

=> 3x - y - 40 = 0 ----(1)

2nd case

marks got for each right answer = 4

marks deducted for each wrong answer = 2

therefore, 4x - 2y = 40

=> 4x - 2y - 40 = 0 ----(2)

comparing equations (1) and (2) with the standard form, we get

a1 = 3 ; b1 = -1 ; c1 = -40

and a2 = 4 ; b2 = -2 ; c2 = -50

now, write that in the form of

x/ b1×c2-b2×c1 = y/c1×a2- c2×a1 = 1/a1×b2-a2×b1

putting the values , we get

x/ 50-80 = y/ -160+150 = 1/ -6+4

=> x/-30 = y/-10 = 1/-2

we can also say that

x/-30 = 1/-2

=> x = -30/-2

=> x = 15

similarly, we can also say that

y/-10 = 1/-2

=> y = -10/-2

=> y = 5

therefore, total number of questions = x+y

= 15+5

=20 :)