SOLUTION: Hi, I need to help my son figure the following problem but don't know where to start! A 34yr old leaves a club and a 64yr old joins, the average age increases by 2. How many

Algebra ->  Average -> SOLUTION: Hi, I need to help my son figure the following problem but don't know where to start! A 34yr old leaves a club and a 64yr old joins, the average age increases by 2. How many      Log On


   

Question 413179: Hi,
I need to help my son figure the following problem but don't know where to start!
A 34yr old leaves a club and a 64yr old joins, the average age increases by 2. How many people are in the club?
Any help gratefully received - I don't want to give him the answer, just help him figure it,
thanks
Found 2 solutions by Alan3354, sudhanshu_kmr:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
The total of the ages increased by 30 (64 - 34)
Avg = total age/# of members
Avg = ages/m (ages is the sum of all members)
Avg + 2 = (ages + 30)/m
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Avg*m = ages
(Avg+2)*m = ages + 30
Avg*m + 2m = ages + 30
ages + 2m = ages + 30
2m = 30
m = 15 members
---------------
This is not as simple a problem as it first seems.



Answer by sudhanshu_kmr(1152) About Me  (Show Source):
You can put this solution on YOUR website!
Let no. of people in the club = x and average age = y
sum of age of all people = x*y
when a 34yr old leaves and a 63yr old joins, then total age = x*y -34 + 64
= x*y + 30 years
average age = (x*y+30)/x
according to question,
(x*y +30)/x = y+2
=> x*y + 30 = x( y+2)
=> x*y + 30 = x*y +2x
=> 2x = 30
=>x= 15

total no. of people in the club = 15