RRB NTPC Prelims Model Paper 5 with solutions

Question : 17 of 100

Marks: +1, -0

The average age of a group of men is increased by 5 years when a person aged 18 years is replaced by a new person aged 38 years. How many men are there in the group ?

Validate

Solution:

2) Let the no. of man in group= n and average is x

∴{ y _1+y_2+ ...+y_{n-1}+18}/n=x

y_1 + y_2+y_ {n-1} +18 =n x

∴ y_1 + y_2 +... + y_{n–1}

= nx –18

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