RRB Group D 23-Oct-2018 Shift 3 Solved Paper

Question : 94 of 100

Marks: +1, -0

The mean of the 5 smallest numbers from a group is 21 while the mean of all the numbers of the group taken together is

25 .

If the mean of the numbers, leaving the smallest five out, is 27.5, how many numbers were there in the group in all?

Solution:

Suppose number is

x

5 \×21+(x-5) \×27.5

=x \×25

5 \×21+27.5 x-27.5 \×5

=x \×25

x(27.5-25)=5(27.5-21)

x={5 \×6.5}/{2.5}=13

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