The hight of the water in an above ground is 3 feet. The pool needs to be drained. As the water changes at a rate of - 1/2 inch per mintues it will take to drain the pool

72 minutes. First convert the height of the pool to inches by multiplying the height in feet by 12 which equals 36. Next multiply that by 2 because the pool is draining at - 1/2 inches per minute, not - 1 inch per minute.