Here are the prices for cans of juice that are the same brand and the same size at different stores. Which store offers the best deal? Store X: 4 cans for $2.48 Store Y: 5 cans for $3.00 *

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?