Basketball Caps


Toni is selling caps for the basketball club. The picture shows the number of caps that Toni sold during the first three weeks.

Week 1

* * * * * * * * *

Week 2

* * * * * *

Week 3

* * *

Week 4

?

How many hats must Toni sell in week 4 so that the average number of caps that she has sold per week is 7?