Complete the chart to find the mean, variance, and standard deviation. Remember to use commas and round numbers to the nearest tenth. X

X

X - X

(X - X )2

1. 45 = -357.5 = The mean is

2. 340 = -62.5 = The variance is

3. 400 = -2.5 = The standard deviation is

4. 825 = 422.5 = n =

Σ X = X = Σ (X - X)2 = 310,225.2

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?