What was the answer to puzzle #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?

Which expression is a perfect cube? a. x8 b. y24 c. m28 d. x64

Grandpa ernie is shrinking! over the past 4 years his height decreased by a total of 2.4 cm.it decreased by the same amount each year. what was the change in grandpa ernie's height each year