Math 146 - Hybrid - Statistics - Spring 2016
Quiz 2 (10 pts)
April 21, 2016
Name: __Anne Sers_______________
1. (1 pt ) After constructing an expanded frequency distribution what should be:
a) the sum of the frequencies?
b) the sum of the relative frequencies?
“n” (sample size) or “N”
1.0 or 100%
2. (1 pt) What is an advantage of using a stem-and-leaf plot instead of a histogram?
Unlike the histogram, the stem-and-leaf plot still contains the original data values.
3. (1 pt )
2
3
4
5
6
7
3
1
1
3
5
5
8
2
1
3
5
9
2
4
3
7
6
8
7
67
7
69
Key: 2 | 3 = 23
What is
a) the range of the data set presented in the stem-and-leaf plot ?
75 - 23 = 52
b) the median? 44
c) the mode? 53 (occurs three times)
4. (1 pt ) True or false:
a) The median is the measure of center most likely to be affected by an outlier. False (mean)
b) About one quarter of a data set falls above Q3. True
5. (1 pt )
a) The symbol used for the variance of a sample is __𝒔𝟐 __.
b) The symbol used for the mean of a population is __µ__.
6. (1 pt) The class levels of 25 students in a physics course are
shown in the table.
Class Level
Freshman
Sophomore
Junior
Senior
Frequency, f
2
5
10
8
a) Which measure of center should be used to describe the data? mode (qualitative data)
b) What is the value of the statistic given in part “a”? (a single value) the mode is: “Junior”
7. (2 pt) a) Give the 5 number summary for the following data sample:
5 16 11 4 5 20 18 9
sorted: 4 5 5 9 11 16 18 20
min: 4 Q1: 5 Q2: 10 Q3: 17 max: 20
b) What is the value of the IQR for the data set? Interpret.
IQR = Q3 - Q1 = 17 - 5 = 12
Interpret  the range of the middle 50% of the data values is 12
8. (1 pt ) The average length of a male glub is 18 inches with a standard deviation of 1 inches. The
average length of a female glub is 14 inches with a standard deviation of 2 inches.
A randomly selected male glub was 15 inches long.
A randomly selected female glub was 18 inches long.
a) Find the z-scores that correspond to each length
zmale = (15 - 18)/1 = -3/1 = -3
zfemale = (18 - 14)/2 = 4/2 = 2
b) Determine if any length is unusual or highly unusual. Explain.
Length of male glub is highly unusual (explain: std devs below mean)
Length of female glub is unusual (explain: 2 std devs above mean)
9. (1 pt ) Give a data set where the mode and the median are equal
For example :
1
3 18
18
18
18
22 41