SOLUTION: The average of three numbers is 12 and that of first two number is 9. Find the third number?
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Question 524950: The average of three numbers is 12 and that of first two number is 9. Find the third number?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let the numbers be ,, and
given:
(1)
(2)
--------------
(2)
(2)
Substitute this back into (1)
(1)
(1)
(1)
(1)
The 3rd number is 18
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