Practice Test Discussion

Q)

The average weight of 45 students in a class was calculated as 36 kg. It was later found that, the weight of two students in the class was wrongly calculated. The actual weight of one of the boys in the class was 32 kg but it was calculated as 34 kg and the weight of another boy in the class was 45 kg, whereas it was calculated as 40 kg. What is the actual average weight of the 45 students in the class? (Rounded off to two digits after decimal)

[PNB Management, 2010]

    • Explanation

    According to the question

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

    ⇒ (32+45)-(34+40)= 45×x

    ⇒ 45×x =3

    ⇒ x= 345=115

    ∴ Actual average = 36+115

     = 36+0.06

     = 36.07 kg

    Hence, Option A is correct.

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