Class Practice on Histograms (2)
1. The data below represents the number of laps done in a swimming pool
by 50 different swimmers last month.
51
30
45
38
20
40
46
50
42
36
52
30
45
38
23
40
46
24
43
35
56
32
45
39
24
40
47
25
43
35
56
32
44
39
60
41
47
26
43
35
57
32
44
40
64
41
50
28
36
32
a. Determine the frequencies for the classes shown below.
Class Boundaries
Frequency f
15 − 20
21 − 26
27 − 32
33 − 38
39 − 44
45 − 50
51 − 56
57 − 62
63 − 68
b.
Construct a histogram for this data. Be sure to label the horizontal
and vertical scales and also to create an appropriate title.
c. Estimate the mean number of laps by examining the histogram.
d. What percent of swimmers swam less than 27 laps? (Show work)
e. What percent of swimmers swam between 27 and 56 laps? (Show work)
f. What percent of swimmers swam more than 56 laps? (Show work)
Answers
a. Determine the frequencies for the classes shown below.
Frequency f
Class Boundaries
1
21 − 26
5
27 − 32
7
33 − 38
7
39 − 44
14
45 − 50
9
51 − 56
4
57 − 62
2
63 − 68
1
Construct a histogram for this data. Be sure to label the horizontal
and vertical scales and also to create an appropriate title.
Laps Done by 50 Swimmers Last Month
14
12
Number of Swimmers
b.
15 − 20
10
8
6
4
2
0
15
21
27
33
39
45
Number of Laps
51
57
63
69
c. Estimate the mean number of laps by examining the histogram.
Somewhere around 39 or 40 or 41, probably.
d. What percent of swimmers swam less than 27 laps? (Show work)
There are 1 + 5 = 6 swimmers that swam less than 27 laps.
6 out of 50 =
6
= 0.12 = 12%
50
e. What percent of swimmers swam between 27 and 56 laps? (Show work)
There are 7 + 7 + 14 + 9 + 4 = 41 swimmers that swam between 27 and 56 laps.
41 out of 50 =
41
= 0.82 = 82%
50
f. What percent of swimmers swam more than 56 laps? (Show work)
There are 2 + 1 = 3 swimmers that swam more than 56 laps.
3 out of 50 =
3
= 0.06 = 6%
50