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Find the mean and the standard deviation of the data set {9, 7, 7, 7, 0}.

A. The mean is 30 and the standard deviation is about 10.
B. The mean is 6 and the standard deviation is about 9.6.
C. The mean is 6.4 and the standard deviation is about 3.16.
D. The mean is 6 and the standard deviation is about 3.1.

User Noam M
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2 Answers

3 votes

Answer:

It is D that is the answer

User Periklis
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3 votes

Answer:

Explanation:

First, let's do the easy part of finding the mean.

we have 5 integers so we add everything in our set and divide by 5.

9+7+7+7+0 = 30 now we shouldn't forget to divide by 5 and 30/5 = 6

The mean is 6 and we rule out options A and C.

The standard deviation is found by doing the following steps:

1. Get the mean of the set (6)

2. subtract each number in the set from the mean and then square the result.

(6-9)^2 = 9

(6-7)^2 = 1

(6-7)^2 = 1

(6-7)^2 = 1

(6-0)^2=36

3. Now, find the mean of the numbers we just got.

9+1+1+1+36 = 48 Now we divide by 5 because of the number of digits in our set. 48/5 = 9.6

4. Finally, we square root 9.6 and we get about 3.1.

The answer is D.

User Jason Pratt
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