Algebra II : Representing Data

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Basic Statistics

Stem_and_leaf

Above is a stem-and-leaf representation of the scores on a test administered to a group of students. What was the mode of the scores?

Possible Answers:

\(\displaystyle 76\)

\(\displaystyle 60\)

\(\displaystyle 64\)

The set of scores has more than one mode.

\(\displaystyle 66\)

Correct answer:

\(\displaystyle 76\)

Explanation:

The mode of the data set is the score that occurs the most frequently.

Each "stem" in the left column represents the tens digits of the scores; each of the numbers in its row, or "leaf" represents the units digits. The entry that occurs the most frequently is represented by the "6" in the "7" row, so 76 is the one and only mode.

Example Question #1 : Representing Data

Stem_and_leaf

Above is a stem-and-leaf plot for the test scores administered to a group of students. 

What was the median score?

Possible Answers:

\(\displaystyle 69\)

\(\displaystyle 76\)

\(\displaystyle 77\)

\(\displaystyle 74\)

\(\displaystyle 66\)

Correct answer:

\(\displaystyle 74\)

Explanation:

Each of the numbers in the leftmost column, or "stems" represents the tens digits of one or more scores; each digit in one of the rows, or "leaf", represents the units digit of a score.

The median score is the score that occurs in the middle when the scores are arranged from least to greatest, which there are, so we count up until we get to the middle score. There are 53, so we look for the 

\(\displaystyle \frac{53 +1}{2} = 27\textup{th }\) highest (or lowest) score. Counting up 27 scores, we get to the "4" in the "7" row, which represents a score of 74. This is the median.

Example Question #2 : Stem And Leaf Plots

List the data values for the given Stem and Leaf plot.

1

Possible Answers:

2, 5, 25, 30, 42, 52, 70, 80

3, 7, 8, 24, 25, 40, 45, 52

3, 7, 8, 24, 25, 45, 52

24, 25, 40, 45, 52

Correct answer:

3, 7, 8, 24, 25, 40, 45, 52

Explanation:

The tens-digits are in the Stem column (left-side) while the ones-digits are in the Leaf column (right-side). Therefore, the data in the Stem and Leaf plot can be written as:

\(\displaystyle 03, 07, 08, 24, 25, 40, 45, 52\)

Example Question #1 : Basic Statistics

List the data values for the given Stem and Leaf plot.

2

Possible Answers:

32, 35, 36, 63, 65, 667, 68, 83, 89

23, 53, 63, 36, 56, 76, 86, 38, 98, 9

32, 35, 36, 63, 67, 68, 83, 89, 90

32, 35, 36, 63, 65, 67, 68, 83, 89, 90

Correct answer:

32, 35, 36, 63, 65, 67, 68, 83, 89, 90

Explanation:

The tens-digits are placed in the Stem column (left-side) and the ones-digits are placed in the Leaf column. Therefore, the data in the Stem and Leaf plot can be written as:

\(\displaystyle 32, 35, 36, 63, 65, 67, 68, 83, 89, 90\)

Example Question #1 : Representing Data

List the data values for the given Stem and Leaf plot. 

3

Possible Answers:

13, 15, 17, 42, 49, 71, 73

31, 51, 71, 24, 94, 17, 37

13, 15, 42, 49, 71, 73

13, 15, 17, 42, 71, 73

Correct answer:

13, 15, 17, 42, 49, 71, 73

Explanation:

The tens-digits are placed in the Stem column (left-side) and the ones-digits are placed in the Leaf column. Therefore, the data in the Stem and Leaf plot can be written as:

\(\displaystyle 13, 15, 17, 42, 49, 71, 73\)

Example Question #5 : Stem And Leaf Plots

List the data values for the given Stem and Leaf plot.

4

Possible Answers:

7, 38, 41, 62, 63, 65, 67

07, 38, 62, 63, 65, 67

70, 83, 14, 26, 23, 25, 27

38, 41, 62, 63, 65, 67

Correct answer:

7, 38, 41, 62, 63, 65, 67

Explanation:

The tens-digits are placed in the Stem column (left-side) and the ones-digits are placed in the Leaf column. Therefore, the data in the Stem and Leaf plot can be written as:

\(\displaystyle 07, 38, 41, 62, 63, 65, 67\)

Example Question #2 : Stem And Leaf Plots

Create the Stem and Leaf plot for the given data values.

\(\displaystyle 4, 6, 22, 34, 54, 95\)

Possible Answers:

5d

5a

5c

5b

Correct answer:

5a

Explanation:

The tens-digits are placed in the Stem column (left-side) and the ones-digits are placed in the Leaf column.

The list of values is: 

34, 54, 6, 95, 22, 4 

This data can also be written as 04, 06, 22, 34, 54, 95

 

5a

Example Question #7 : Stem And Leaf Plots

Create the Stem and Leaf plot for the given data values:

6, 8, 10, 23, 35, 43, 44, 45, 48

Possible Answers:

6a

6c

6b

6d

Correct answer:

6a

Explanation:

The tens-digits are placed in the Stem column (left-side) and the ones-digits are placed in the Leaf column.

The data values are: 

6, 8, 10, 23, 35, 43, 44, 45, 48

We can rewrite it as follow

06, 08, 10, 23, 35, 43, 44, 45, 48

6a

 

Example Question #9 : Representing Data

Which of the following represents the correct median value of the above Stem and Leaf Plot?

Possible Answers:

\(\displaystyle 74\)

\(\displaystyle 80\)

\(\displaystyle 73.5\)

\(\displaystyle 71.\bar{3}\)

Impossible to determine based on the data provided.

Correct answer:

\(\displaystyle 74\)

Explanation:

There are 18 data points in this set, so the median lies halfway between the 9th and 10th sequential data point:

9th Point: \(\displaystyle 73\)

10th Point: \(\displaystyle 75\)

 

And:

 

\(\displaystyle \frac{75+73}{2}= \frac{128}{2}=74\)

 

The correct median value of the data set is 74

Example Question #1 : Box And Whisker Plots

Draw a Box and Whisker plot for the following data set.

\(\displaystyle 2, 8, 10, 14, 18, 19, 39\)

Possible Answers:

1a

1c

1d

1b

Correct answer:

1a

Explanation:

Put the data in numerical order (from smallest to largest) if it isn't already. In order to find the median, divide the data into two halves. In order to divide the values into quartiles, find the median of the two halves. 

 

\(\displaystyle 2, 8, 10, 14, 18, 19, 39\)

1st quartile: \(\displaystyle 2\)\(\displaystyle 8\)\(\displaystyle 10\)

Median of 1st quartile: \(\displaystyle 8\)

 

2nd quartile = Median of total set: \(\displaystyle 14\)

 

3rd quartile: \(\displaystyle 18\)\(\displaystyle 19\)\(\displaystyle 39\)

Median of 3rd quartile: \(\displaystyle 19\)

 

To construct the Box and Whisker Plot we use the minimum and the maximum value in the data set as the ends of the whiskers. To construct the box, we plot a line at the median of the 1st quartile, the median of our total data set, and at the median of the 3rd quartile. Then we connect the tops and bottom of the lines. The result is as follows: 

1a

The endpoints (black dots) represent the smallest and largest values, in this case, 2 and 39.

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