Standard Deviation

Question 1

What is standard deviation used for?

Answer 1

To measure spread. It looks at how far away the individual numbers are from the mean.

Question 2

How can the standard deviation be found for frequency tables?

Answer 2

1. Find fx for all the x values.
2. Find fx^2 for all the x values.
3. In the standard deviation formula, put an f before all the x’s and replace n with Σf.

Question 3

How can the standard deviation be found for grouped frequency tables?

Answer 3

1. X is the midpoint.

2. Follow the same method as for frequency tables.

Question 4

What happens to the mean if all the values change by the same amount?

Answer 4

The mean increases by said amount.

Question 5

What happens to the standard deviation of all the values change by the same amount?

Answer 5

The standard deviation stays the same.

Question 6

What happens to the mean if all the values are multiplied or divided by the same amount?

Answer 6

The mean is multiplied by said amount.

Question 7

What happens to the standard deviation if all the values are multiplied or divided by the same amount?

Answer 7

The standard deviation is multiplied by said amount.

Question 8

How can variance be calculated?

Answer 8

By squaring the standard deviation.