Find the unit price and choose the better buy. 80 oz bottle of cleaner for $13.60
70 oz bottle of cleaner for $13.30
90 oz bottle of cleaner for $18.00
60 oz bottle of cleaner for $10.80

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?