Practice Test Discussion

Q)

A cricketer has a mean score of 60 runs in 10 innings. Find out how many runs are to be scored in the 11 innings to raise the mean score to 62?

[RRB, 2015]


  • Explanation

    Here we can use the formula

    Average (A)=Sum of observations (S)No. of observations (N) ⇒ S=A×N

    According to the question,

    Sum of runs in 10 innings (A=60, N=10)

    ⇒S=60 X 10 =600

    Later, In how many runs are to be scored in the 11 innings to raise the mean score to 62 (so A=62, N=11)

    So, sum of 7 observations

    ⇒S=62 X 11 =682

    Now,

    Score of 11th innings =(sum of runs in 10 innings)-(Sum of runs in 11 innings)

    =682-600

    = 82

    Hence, Option D is correct.

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    Average

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