Practice Test Discussion

Q)

Jatin gets 3 marks for each correct sum and loses 2 marks for each wrong sum. He attempts 30 sums and obtains 40 marks. The number of sums solved correctly is ?

    • Explanation

    Given that,

    Let the question solved by jatin= X

    and number of question solved wronglly by jatin= Y

    According ti the question,

    we get,

    ⇒ X+Y=30   -----(1)

    ⇒ 3X+2Y=40 ----(2)

    Now, multiply the equations (1) and (2)

    we get,

    ⇒ 2X+2Y=60 ----(3)

    After adding the equation (2) and (3) we get,

    ⇒ 3X-2Y+2X+2Y=40+60

    ⇒ 5X=100

    ⇒ X=20

    ∴ Jatin attempted 20 question correctly.

    Hence, Option A is correct.

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