if the average of six numbers is 10, and five of them are 5, 8, 12, 15, and 17, what is the sixth number?

Answer 1

The average of six numbers is 10

and the numbers are 5, 8, 12, 15, 17

so when this numbers are added and divided with 6 we should get 10

which means, 5+8+12+15+17+x =10

                                      6

where x is the sixth number

so 57+x =10

6

57+3= 60/6 =10

    6

so the sixth number is 3.