SOLUTION: The oldest child in a family of four children is twice as old as the yougest. The two middle children are 13 and 15 years old. If the average age of the children is 14.5 , how old

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Question 313459: The oldest child in a family of four children is twice as old as the yougest. The two middle children are 13 and 15 years old. If the average age of the children is 14.5 , how old is the youngest child?

Found 2 solutions by unlockmath, ankor@dixie-net.com:
Answer by unlockmath(1688) (Show Source):
You can put this solution on YOUR website!
Hello,
Let's have x represent the youngest and 2x will show the oldest. Now we can find the average by:
(x+13+15+2x)/4=14.5 Rewritten as:
(3x+28)/4=14.5 Multiply both sides by 4 to get:
3x+28=58 Subtract 28 and divide by 3 to get:
x=10 So the youngest is 10 years old the oldest is 20.
Make sense?
RJ
www.math-unlock.com

Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
The oldest child in a family of four children is twice as old as the youngest.
The two middle children are 13 and 15 years old.
If the average age of the children is 14.5, how old is the youngest child?
:
Let x = the youngest child
then
2x = the oldest child
:
"the average age of the children is 14.5,"
= 14.5
:
= 14.5
Multiply both sides by 4
3x + 28 = 4(14.5)
3x + 28 = 58
3x = 58 - 28
3x = 30
x =
x = 10 yrs is the youngest child
:
:
Check solution (oldest child = 20)
=
= 14.5