Practice Test Discussion

Q)

The average marks in biology subject of a class of 24 students is 56. if the marks of three students were misread as 44, 45 and 61 of the actual marks 48, 59  and 67 respectively, then what would be the correct average?

    • Explanation

    According to the question,

    We know the formula,

    Sum of the added quantities - Sum of removed quantities= ±Nx

    ⇒ (44+45+61)-(48+59+67)= -24x

    ⇒ 150-174= -24x

    ⇒ x=-24-24=1

    ∴ The correct average= 56+1 =57

    Hence, Option D is correct.

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