SOLUTION: the mean age of four boys is 7. A new boy joins the group and the mean age increases to 8. What is the age of the new boy?

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Question 880885: the mean age of four boys is 7. A new boy joins the group and the mean age increases to 8. What is the age of the new boy?
Answer by JulietG(1812) About Me  (Show Source):
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Mean age of 7 * 4 boys = 28
Mean age of 8 * 5 boys = 40
The new boy is 40-28, or 12