The Jakobshavn Glacier in Greenland, reputed to be the fastest in the world, has sped up lately (perhaps due to global warming?). The last accurate measurements have it travelling at 5.25 kilometers (5250 meters) in a five month period. At this rate, how far does it travel in a year?

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?