Mean, Deviation (DEV), and Average (DEV)? question

[lolzwhut?]

For the following data set of eight values, give the MEAN, DEVIATION (DEV), and AVERAGE DEVIATION (AD). Show a sample calculation for each: 0.77, 0.92, 1.12, 1.00, 0.96, 0.88, 1.16, 1.02

Homework Equations

Well before we began, can anyone take the courtesy and see if I'm getting the correct answer?

MEAN: 0.97875
DEV: .0126 (maybe?)
AD: ?

The Attempt at a Solution

DEV:
(-167/800)^2+(-47/800)^2+(113/800)^2+(-3/160)^2+(-79/808)^2+(29/160)^2+(33/800)^2 = 0.111635/(8-1) = 0.0159 =sqrt(0.0159)=0.126

I'm confused now...I think I found the standard deviation. However, I'm unsure how to even calculate the average deviation cause I don't have enough values. what am i doing wrong? What should I do next?

 

[lanedance]

mean looks good
$$\mu = \frac{1}{n}\sum_i x_i$$
terminology, generally I would consider:
standard deviation (square root of variance)
$$\sigma = \sqrt{\frac{1}{n}\sum_i (x_i-\mu)^2}$$
sample standard deviation (square root of sample variance)
$$s = \sqrt{\frac{1}{n-1}\sum_i (x_i-\mu)^2}$$

can you give your formulas for each DEV and AD?

looks like you are calculating the sample deviation (based on the (8-1) term)

 

[lanedance]

DEV:
(-167/800)^2+(-47/800)^2+(113/800)^2+(-3/160)^2+(-79/808)^2+(29/160)^2+(33/800)^2 = 0.111635/(8-1) = 0.0159 =sqrt(0.0159)=0.126

Also though I cpiece together what you are attempting, writing it like this may confuse things for other people, in particular

0.0159 =sqrt(0.0159)

which doesn't make any senseit would be better to be break it up into

DEV^2 = (-167/800)^2+(-47/800)^2+(113/800)^2+(-3/160)^2+(-79/808)^2+(29/160)^2+(33/800)^2 = 0.111635/(8-1) = 0.0159

DEV=sqrt(0.0159)=0.126

sorry if it comes across as pedantic, but if its clear what you're attempting you'll generally get a better and quicker answer (probably in test as well)