SOLUTION: The average of 30 numbers is 12. The average of first 20 of them is 11 and that of next 9 is 10. The last number is :

Algebra ->  Average -> SOLUTION: The average of 30 numbers is 12. The average of first 20 of them is 11 and that of next 9 is 10. The last number is :       Log On


   

Question 830715: The average of 30 numbers is 12. The average of first 20 of them is
11 and that of next 9 is 10. The last number is :
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
30*12-20*11-9*10=n
n=50