Explanation:
The circumference of Carlos' head is 22 inches. He want to but a cap. He must know the size of the cap. The formula of circumference of circular shaped object is given by :
![C=2\pi r](https://img.qammunity.org/2021/formulas/mathematics/middle-school/mi4tnw17egix4j0slvrtb6r082cjra53zk.png)
r is radius of cap
or
Diameter of cap, D = 2 r = 7 inches
So, he must buy a cap that have diameter of 7 inches.