Answer:
13 gallons
Step-by-step explanation:
The circumference of the silo is ...
πd = 28π ft = 87.965 ft
The area is the product of this length and the height of the silo, ...
(87.965 ft)(42 ft) ≈ 3694 ft²
This is about 12.32 times 300 square feet. If we assume that Jack can only acquire whole gallons, Jack will need 13 gallons of paint.