Acontractor records the areas, in square feet, of
several houses in a neighborhood to determine
data about the neighborhood. which formula
should be used to calculate the standard
deviation?

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?