The number a x 10^-2 is about 8 times greater than b x 10^-3
find the correct value of a and b
a. a = 3.1 and b = 2.5
b. a = 2.5 and b = 3.1
c. a = 2 and b = 1.2
d. a = 1.2 and b = 2

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?