RRB Group D 13-Dec-2018 Shift 2 Solved Paper

Question : 19 of 100

Marks: +1, -0

The mean of the five smallest numbers from a group is 22 , while the mean of all the numbers of the group taken together is 26. If the mean of the numbers excluding the smallest five out is 28.5, how many numbers were there in the group in all?

Validate

Solution:

Given

s_5=22×5=110

Let total number=

n

∴s_5+s_R=26×n

s_R=26n-110

....(1)
Also,

s_R=28.5(n-5)

...(2)
From (1) and (2),

28.5(n-5)=26n-1100

28.5n-142.5=26n-110

2.5n=32.5

n=13

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