The main goal of personal financial planning is: saving and investing for future needs. reducing a person's tax liability. achieving personal economic satisfaction. spending to achieve financial objectives. saving, spending, and borrowing based on current needs.

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?