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10.085 Stem and leaf plots

Worksheet
Stem-and-leaf plots
1

State whether the following is true about an ordered stem-and-leaf plot:

a

The scores are ordered.

b

A stem-and-leaf plot does not give an idea of outliers and clusters.

c

It is only appropriate for data where scores have high frequencies.

d

The individual scores can be read on a stem-and-leaf plot.

2

Construct a stem-and-leaf plot that represents the following data:

24,\, 26,\, 25,\, 37,\, 36,\, 37,\, 37,\, 38,\, 41,\, 46,\, 49,\, 56,\, 67,\, 63,\, 67,\, 68,\, 69,\, 75,\, 80,\, 80

3

Complete the following frequency table for the data displayed in the adjacent stem-and-leaf plot:

ScoreFrequency
10-19
20-29
30-39
40-49
50-59
Leaf
11\ 2\ 3\ 7
23\ 4\ 7\ 7\ 7\ 9
32\ 7\ 9
40\ 1\ 1\ 5\ 6
52\ 6

Key: 1|2=12

4

The stem-and-leaf plot shows the age of people to enter through the gates of a concert in the first 5 seconds:

a

How many people passed through the gates in the first 5 seconds?

b

What was the age of the youngest person?

c

What was the age of the oldest person?

d

What proportion of the concert-goers were under 25 years old?

Leaf
12\ 4\ 5\ 6\ 6\ 9\ 9
21\ 2\ 6\ 7\ 8\ 9\ 9
31\ 3\ 8\ 8
4
55

Key: 1|2= 12 years old

5

The scores for a recent spelling test are shown in the stem-and-leaf plot. The maximum possible score on the test was 100.

a

How many students took the test?

b

What was the highest score on the test?

c

What test score occurred the most frequently?

d

How many marks separate the highest score and the most frequent score?

Leaf
62\ 3\ 3\ 6\ 6\ 7
70\ 1\ 1\ 1\ 1\ 4\ 5\ 8
81\ 1\ 2\ 3\ 4\ 5\ 6\ 9\ 9\ 9
94\ 5\ 7\ 9

Key: 6|2=62

6

The level of mercury in 40 fishing waters was tested and recorded. The results are given in the following stem-and-leaf plot:

a

What was the second highest reading?

b

In how many places was a reading of 117 or higher recorded?

c

What was the 11th lowest score?

d

If the safe level of mercury is recommended to be 109 or lower, what percentage of the places have safe levels of mercury?

Leaf
91\ 3\ 5\ 5\ 6
101\ 2\ 4\ 4\ 5\ 5\ 6\ 8\ 9\ 9
111\ 1\ 2\ 3\ 3\ 3\ 5\ 6\ 7\ 7\ 7\ 8\ 8\ 8\ 8\ 9
122\ 2\ 2\ 2\ 2\ 3\ 4\ 6\ 9

Key: 1|2=12 units

7

A cyclist measured his heart rate immediately after finishing each event in which he competed. The results are recorded in a stem-and-leaf plot, but two values are missing:

a

He can remember no number appears twice in the plot. What is the smaller missing number?

b

If both missing numbers sum to 367, what is the second missing number?

Key: 12|3= 123

8

The size of each earthquake that occurred over a three year period, measured from 0 to 9.9, is recorded in the following stem-and-leaf plot:

a

What was the size of the largest earthquake measured?

b

An earthquake of size 6 or greater causes significant damage to buildings. How many of the earthquakes caused significant damage to buildings?

c

Students are asked to randomly choose an earthquake to report on.

What is the probability that the first person picks an earthquake that measured between 8 and 9 (inclusive)?

Leaf
09
11\ 5
21\ 2\ 2\ 3\ 3\ 5\ 6\ 6\ 6\ 7\ 9\ 9
30\ 2\ 8
40\ 6\ 6\ 8\ 8\ 9
55\ 7\ 7\ 8
60\ 2\ 4\ 4\ 9
71\ 5\ 7
80\ 4\ 5\ 8

Key: 4|6=4.6

Back-to-back stem-and-leaf plots
9

The following stem-and-leaf plot shows the results of a survey conducted on the price of concert tickets locally and the price of the same concerts at an international venue:

a

What was the most expensive ticket price at the international venue?

b

At the international venue, what percentage of tickets cost between \$90 and \$110 (inclusive)?

c

At the local venue, what percentage of tickets cost between \$90 and \$100 (inclusive)?

LocalInternational
8\ 5\ 5\ 063\ 9
9\ 7\ 6\ 5\ 072\ 4\ 7\ 7
7\ 4\ 1\ 1\ 080\ 3\ 4\ 8
3\ 3\ 3\ 2\ 091\ 1\ 1\ 2\ 3
9100\ 1\ 1\ 3\ 9

Key: 6|1|2 = 16 \text{ and } 12

10

The stem-and-leaf plot shows the batting scores of two cricket teams, the Grasshoppers and the Cicadas:

a

What is the highest score for the Grasshoppers?

b

What is the highest score for the Cicadas?

GrasshoppersCicadas
5\ 030\ 3\ 5\ 6\ 8
8\ 7\ 6\ 4\ 4\ 142\ 6
7\ 353\ 5
65

Key: 6|1|2 = 16 \text{ and } 12

11

The test scores of 12 students in Music and French are listed below:

  • Music: \ 79,\, 59,\, 74,\, 94,\, 51,\, 71,\, 93,\, 84,\, 69,\, 61,\, 86,\, 86

  • French: \ 62,\, 71,\, 64,\, 82,\, 83,\, 99,\, 87,\, 89,\, 66,\, 73,\, 59,\, 76

Display the data as an ordered back-to-back stem-and-leaf plot.

12

Two friends have been growing sunflowers. They have measured the height of their sunflowers to the nearest centimetre, with their results shown below:

  • Oliver:\ 15,\, 25,\, 19,\, 15,\, 34,\, 44,\, 38,\, 27

  • Valentina:\ 7,\, 45,\, 14,\, 22,\, 43,\, 16,\, 21,\, 26,\, 29,\, 49,\, 8,\, 35,\, 2

Display the data as an ordered back-to-back stem-and-leaf plot.

13

The data below represents how long each student in two different classes could hold their breath for, measured to the nearest second:

  • Dr Patel's class: 46,\, 34,\, 11,\, 37,\, 64,\, 29,\, 57,\, 17,\, 55,\, 53,\, 63,\, 25,\, 66,\, 49,\, 34

  • Mr Jones's class: 43,\, 44,\, 67,\, 34,\, 31,\, 23,\, 52,\, 15,\, 18,\, 49,\, 12,\, 55,\, 41,\, 65,\, 26

a

Display the data as an ordered back-to-back stem-and-leaf plot.

b

Who is the teacher of the student who can hold their breath the longest?

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Outcomes

MS11-2

represents information in symbolic, graphical and tabular form

MS11-7

develops and carries out simple statistical processes to answer questions posed

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