Question 984869: the mean age of 10 people is 15. When another person joins the group, the mean age goes down to 14. How old os the new person? Answer by macston(5194) (Show Source):
You can put this solution on YOUR website! The sum of the ages of the original group was
(Number of people)x(average(mean))=(10)(15)=150 years
Adding one person, the sum to have a mean of 14 is
(Number of people)x(average(mean))=(14)(11)=154 years
154 years-150 years=4 years
ANSWER The 11th person was 4 years old.
