4gallons of paint are used to paying 25 chairs if each chair used the same amount of paint how many gallons are used to paint each chair between what two whole numbers does my answer lie between

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?