SOLUTION: The average age of Ramona's three cousins is 13. One of her cousins is 7 years old and another is 15 years old. How old is the third cousin?

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Question 1112037: The average age of Ramona's three cousins is 13. One of her cousins is 7 years old and another is 15 years old.
How old is the third cousin?
Found 2 solutions by ikleyn, MathTherapy:
Answer by ikleyn(52802)   (Show Source): You can put this solution on YOUR website!
.
 = 13         <<<---=== I edited my typo after the @MathTherapy post.   Thanks @MathTherapy for noticing the typo !


7 + 15 + x = 13*3


22 + x = 39


x = 39 - 22 = 17.

Answer.   Third cousin is  17  years old.

Check.     Do the check on your own.


Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

The average age of Ramona's three cousins is 13. One of her cousins is 7 years old and another is 15 years old.
How old is the third cousin?
Third and oldest cousin is:  

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