what is the mean of all 15 numbers?

Question

the mean of 6 numbers is 11 the mean of a different set of 9 numbers is 6

Answer 1

The sum of the first 6 numbers is 6*11.  The sum of the second set of number is 9*6.  There are 6+9 numbers in total.

 

Mean = (6*11 + 9*6)/(6+9) = ______