Practice Test Discussion

Q)

The average marks of 65 students in a class was calculated as 150. It was later realised that the marks of one of the student was calculated as 142, where as his actual marks were 152. What is the actual average marks of the group of 65 students? (rounded off to two digits after decimal)

[Syndicate Bank, 2009]

    • Explanation

    According to the question

    The value of new quantity added - value of removed quantity= ± Nx

    ⇒ 152-142= ±N×x

    ⇒ 10= 65×x

    ⇒ x=1065

    So, actual average = 150+1065

        = 150+0.15

        = 150.15

    Hence, Option B is correct.

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