Thread: standard deviation

I did these questions but im not sure if they are 100% correct since the back of the book is not showing the same answers (my teacher said the book could be wrong alot of the time).

3. Calculate the standard deviation for the following:

(17,18, 19, 20, 21, 22, 23, 24, 25, 26)

5. Find the quartile values, the interquartile range, and the standard deviation of the salaries listed below.

Salary Frequency
28000 4
30000 6
32000 7
34000 4
36000 2
38000 1

Great. What did you get when you did them?

Originally Posted by Skoz

I did these questions but im not sure if they are 100% correct since the back of the book is not showing the same answers (my teacher said the book could be wrong alot of the time).

3. Calculate the standard deviation for the following:

(17,18, 19, 20, 21, 22, 23, 24, 25, 26)

Mr F says: 3.028. (It's possible your book might give 2.872)

5. Find the quartile values, the interquartile range, and the standard deviation of the salaries listed below.

Salary Frequency
28000 4
30000 6
32000 7
34000 4
36000 2
38000 1

Mr F says:Q1 = 30000, Q2 = 32000, Q3 = 34000, IQR = Q3 - Q1, sd = 2722.69 (it's possible your book might give 2665.36)

Doesn't your teacher have correct answers that s/he can give you?

No he doesn't give it... ;/

I'm pretty sure there are 2 standard deviation equations. Maybe the book and you used different equations. This site gives the 2 equations I'm thinking of:

Standard Deviation Calculation