I have to paint one side of a wall. The wall is $15$ meters tall and $60$ meters long. Each gallon of paint covers $400$ square feet. If a foot is approximately $0.3048$ meters, then what is the smallest whole number of gallons I can buy and have enough paint to cover the whole wall?
The dimensions of the wall in feet are 15 / 0.3048 = 49.2126 ft and 60 / 0.3048 = 196.8504 ft. This means that the area of the wall is 49.2126 * 196.8504 = 9.687.52 feet. Since 9600 (400 * 24) < 9687.52 < 10000 (400 * 25), you will need 25 gallons of paint to paint the wall.