Final Exam
Review Questions
Solutions Guide
You will probably want to PRINT THIS so you can carefully
check your answers. Be sure to ask your instructor if you have
questions about any of the solutions given below.
1. Explain the difference between a population and a sample. In
which of these is it important to distinguish between the two in order
to use the correct formula? mean; median; mode; range; quartiles;
variance; standard deviation.
Solution: A sample is a subset of a population. A population consists
of every member of a particular group of interest. The variance and
the standard deviation require that we know whether we have a
sample or a population.
2. The following numbers represent the weights in pounds of six
7- year old children in Mrs. Jones' 2nd grade class.
{25, 60, 51, 47, 49, 45}
Find the mean; median; mode; range; quartiles; variance; standard
deviation.
Solution: mean = 46.17
median = 48
mode does not
exist range = 35.00
Q1 = 40.0
Q2 = median =
48.0 Q3 = 53.25
variance = 134.57
standard deviation =11.60
3. If the variance is 846, what is the standard deviation?
Solution: standard deviation = square root of variance = sqrt(846) =
29.086
4. If we have the following data
Page 1 of 11
, 34, 38, 22, 21, 29, 37, 40, 41, 22, 20, 49, 47, 20, 31, 34, 66
Draw a stem and leaf. Discuss the shape of the distribution.
Solution:
2|219200
3|48714
4|0197
5|
6|6
This distribution is right skewed (positively skewed) because the “tail”
extends to the right.
5. What type of relationship is shown by this scatter plot?
4
5
4
0
3
5
3
0
2
5
2
0
1 0 5 1 1 2
5 0 5 0
1
0
5
0
Solution: Weak positive linear correlation
6. What values can r take in linear regression? Select 4 values in this
interval and describe how they would be interpreted.
Solution: the values are between –1 and +1 inclusive.
-1 means strong negative correlation
+1 means strong positive
correlation 0 means no correlation
.5 means moderate positive correlation
etc.
7. Does correlation imply causation?
Solution: No.
Page 2 of 11
Review Questions
Solutions Guide
You will probably want to PRINT THIS so you can carefully
check your answers. Be sure to ask your instructor if you have
questions about any of the solutions given below.
1. Explain the difference between a population and a sample. In
which of these is it important to distinguish between the two in order
to use the correct formula? mean; median; mode; range; quartiles;
variance; standard deviation.
Solution: A sample is a subset of a population. A population consists
of every member of a particular group of interest. The variance and
the standard deviation require that we know whether we have a
sample or a population.
2. The following numbers represent the weights in pounds of six
7- year old children in Mrs. Jones' 2nd grade class.
{25, 60, 51, 47, 49, 45}
Find the mean; median; mode; range; quartiles; variance; standard
deviation.
Solution: mean = 46.17
median = 48
mode does not
exist range = 35.00
Q1 = 40.0
Q2 = median =
48.0 Q3 = 53.25
variance = 134.57
standard deviation =11.60
3. If the variance is 846, what is the standard deviation?
Solution: standard deviation = square root of variance = sqrt(846) =
29.086
4. If we have the following data
Page 1 of 11
, 34, 38, 22, 21, 29, 37, 40, 41, 22, 20, 49, 47, 20, 31, 34, 66
Draw a stem and leaf. Discuss the shape of the distribution.
Solution:
2|219200
3|48714
4|0197
5|
6|6
This distribution is right skewed (positively skewed) because the “tail”
extends to the right.
5. What type of relationship is shown by this scatter plot?
4
5
4
0
3
5
3
0
2
5
2
0
1 0 5 1 1 2
5 0 5 0
1
0
5
0
Solution: Weak positive linear correlation
6. What values can r take in linear regression? Select 4 values in this
interval and describe how they would be interpreted.
Solution: the values are between –1 and +1 inclusive.
-1 means strong negative correlation
+1 means strong positive
correlation 0 means no correlation
.5 means moderate positive correlation
etc.
7. Does correlation imply causation?
Solution: No.
Page 2 of 11
