Question

What is the standard deviation of the following data set rounded to the nearest tenth?

7.7, 8.4, 9, 8, 6.9

a.0.4
b.0.7
c.0.5
d.0.8

Answer 1

It takes a while to do the standard deviation. To find the standard deviation, you want to first find the mean of the data set. So what is the mean?

Answer 2

8.2

Answer 3

Are you sure you did it right? I got 8.

Answer 4

nevermind i got 8 now

Answer 5

Alright. Next, you want to subtract the mean from each data.
So:
7.7 - 8 = ?
8.4 - 8 = ?
9 - 8 = ?
8 -8 = ?
6.9 - 8 =?

Fill in the question mark please.

Answer 6

-.3
.4
1
0
-1.1

Answer 7

Alright. Next, you want to square them.
-0.3^2 =
.4^2 =
1^2 =
0^2 =
-1.1^2 =

Answer 8

.09
.16
1
0
1.21

Answer 9

Next, you want to find the mean of it. What is the mean of it?

Answer 10

.492 or .5

Answer 11

It's .492.
Now, .492 is the variance.
To find the standard deviation, you want to square root it.
So what's the square root of .492?

Answer 12

.7

Answer 13

Yes. So the standard deviation of that data set it 0.7.
I hope this help!
Also, http://www.mathsisfun.com/data/standard-deviation.html will help you solve these questions.

Answer 14

awesome