Determine the area under the standard normal curve that lies between: z = 1 & z= 3

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?

Percent increase and decrease. original number: 45 new number: 18

Of the 304 people who attended a school play, 5/8 were students. how many of the people who attended were students.