Free Printable Standard deviation with stem and leaf practice

1.

Find the mean and the standard deviation of a sample with data;

$\Sigma x=960,\ \Sigma x^2=18000\ and\ n=60$

a)

mean = 16

standard deviation = 6.63

b)

mean = 18.75

standard deviation = 43.96

c)

mean = 16

standard deviation = 43.96

d)

mean = 18.75

standard deviation = 6.63

2.

Find the mean and the standard deviation of a sample with data;

$\Sigma\left(x-\overline{x}\right)=2000,\ \Sigma x=960\ and\ \Sigma f=60$

a)

mean = 16

standard deviation = 5.77

b)

mean = 2.08

standard deviation = 33.33

c)

mean = 33.33

standard deviation = 5.77

d)

mean = 2.08

standard deviation = 5.77

3.

For a set of 20 items of data Σx = 22 and $\Sigma x^2=55$ . Find the mean of the data.

(a)

4.

For a set of 20 items of data Σx = 22 and $\Sigma x^2=55$ . Find the standard deviation of the data. (give your answer to 2 decimal places)

(a)

5.

For a data set of 50 items of data $\Sigma\ f\left(x-\overline{x}\right)^2=8\ and\ \Sigma fx=20$ ,

Find the mean of the data.

(a)

6.

For a data set of 50 items of data $\Sigma\ f\left(x-\overline{x}\right)^2=8\ and\ \Sigma fx=20$ ,

Find the standard deviation of the data.

(a)

7.

As part of a biology experiment Thabo caught and weighed 120 minnows. He

used his calculator to find the mean and standard deviation of their weights.

Mean 26.231 g

Standard deviation 4.023 g

Find the total weight, Σx, of Thabo’s 120 minnows.

(give your answer to 2 decimal places and leave out the unit when writing your answer)

(a)

8.

Calculate the standard deviation of the 50 reading test scores given that;

$\Sigma fx\ =\ 3250\ and\ \ \Sigma fx^2\ =\ 217850$

(give your answer to 1 decimal place)

(a)

9.

What is the standard deviation for the data given:

{5, 10, 7, 12, 0, 20, 15, 22, 8, 2}

a)

6.89

b)

10.1

c)

7.26

d)

9

10.

All of the below sets have the same mean.
Set 1-Standard Deviation=3.1
Set 2-Standard Deviation=4.9
Set 3-Standard Deviation=1.7
Set 4-Standard Deviation=3.2
Which set of data probably has the points closest to the mean?

a)

1

b)

2

c)

3

d)

4

11.

The box-and-whisker plot below shows the number of points each member of the middle school basketball team made during the game on Saturday. What was the greatest number of points scored by a basketball player during the game on Saturday?

a)

4

b)

6

c)

7

d)

8

12.

Andy recorded the heights of the boys and girls in his class in the double stem-and-leaf plot. What is the difference in height between the tallest boy and the tallest girl?

a)

2 inches

b)

4 inches

c)

13 inches

d)

19 inches

13.

The distribution of annual salaries for the 21 employees in a small company has a median of $45,000 and a standard deviation of $10,000. The owner of the company promotes one of the employees and the employee’s salary increases from $65,000 a year to $95,000 a year. What impact will this salary increase have on the median and the standard deviation of annual salaries for this company?

a)

Both the median salary and the standard deviation will change.

b)

Neither the median salary nor the standard deviation will change.

c)

The median salary will increase, but the standard deviation will not change.

d)

The median salary will not change, while the standard deviation will increase.

14.

A set of 16 data values, x, has $\Sigma\left(x-\overline{x}\right)^2=36$