Question

The average age of group of friends is 25years.If four new friends with an average age of 21year join the group the average of the entire group become 23 years.How many friends were there initially?

Answer 1

Hi there!

Your answer is in the attachment.

Answer 2

There are 4 friends initially.

Step-by-step explanation:

Since we have given that

Average age of group of friends = 25 years

Number of friends added = 4

Average age of them = 21 years

So, the average age of entire group = 23 years.

So, it becomes,

$\dfrac{25x+21\times 4}{x+4}=23\\\\\dfrac{25x+84}{x+4}=23\\\\25x+84=23(x+4)\\\\25x+84=23x+92\\\\25x-23x=92-84\\\\2x=8\\\\x=\dfrac{8}{2}=4$

Hence, there are 4 friends initially.

# learn more:

The average age of group of friends is 25years.If four new friends with an average age of 21year join the group the average of the entire group become 23 years.How many friends were there initially?

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