Need help with some retakes

According to the normal model, what percent of receivers would you expect to gain fewer yards than 2 standard deviations below the mean number of yards

Kayaks rent for $35 per day. which expression can you use to find the cost in dollars of renting 3 kayaks for a day?

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?