SOLUTION: 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?

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.
RELATED QUESTIONS
the mean age of 10 people is 15. When another person joins the group, the mean age goes... (answered by solver91311)

The mean age of a group of eight girls was 15. One more girl joins the group and the mean (answered by harpazo)

the mean weight of 7 people is 61kg. another person joins the group and the mean falls to (answered by fcabanski)

the mean age of four boys is 7. A new boy joins the group and the mean age increases to... (answered by JulietG)

the mean age of 3 people is 22 and their median age is 20. the range of their ages is 16. (answered by stanbon)

the mean age of four women is 19year 11month. When a fifth woman joins them, the average... (answered by ankor@dixie-net.com)

12. The director of admissions estimates admissions based on past experieces.... (answered by Boreal)

The combined age of two people is 91. Person A is twice as old as person B was when... (answered by AnlytcPhil)

The average age of 6 person is 25 years.the average of the group when a 45 years old... (answered by Cromlix)