Jose deposits $1500 of his tax refund into an account that earns simple annual interest. how much interest will his account earn after 6 years at an annual interest rate of 4%?

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?