On a line plot, there are 4 X marks stacked above the number 6. What does this tell you?
AFour data points had a value of 6
BThere are 6 data points in the whole data set
CThe number 6 appeared last in the list of data
D6 is the average of all the data values
Each X mark represents one data point. Four X's above 6 means four observations recorded the value 6. The height of the stack equals the frequency — how often that value appeared. Option B confuses the value on the number line (6) with the count of X marks (4). To find the total number of data points, you add up all the X marks across the entire plot, not read a single value on the number line.
Question 2 Multiple Choice
A class records how many books each student read. Their line plot shows the tallest stack of X marks above the number 5. Which conclusion is correct?
AMore students read exactly 5 books than any other number of books
BStudents read a combined total of 5 books
CThe average number of books read was 5
DThe line plot only shows data for 5 students
The tallest stack above a value means that value appeared most frequently in the data — more students had that exact count than any other. This is called the mode. Option B confuses the value (5) with the total count. Option C (average/mean) requires computation using all data values and cannot be read directly from which stack is tallest. Option D misreads the number 5 as a count of students rather than a data value.
Question 3 True / False
To create an accurate line plot, X marks above each value must be stacked directly above one another so that column heights correctly show frequency.
TTrue
FFalse
Answer: True
Neat vertical alignment is not just aesthetic — it is what makes the plot readable. If X marks are scattered or uneven, stacks of different frequencies can look the same height, making comparisons misleading. The whole point of a line plot is that the visual height of each column communicates frequency at a glance. Misaligned marks undermine that purpose.
Question 4 True / False
The total number of data points in a line plot equals the largest number shown on the number line scale.
TTrue
FFalse
Answer: False
The total number of data points equals the total number of X marks on the plot — you find it by counting or adding up all the marks, not by reading the scale. The number line scale shows the possible data values, not the count of observations. For example, a line plot with a scale from 1 to 10 could show 30 students' data if each student recorded one measurement. The scale range and the sample size are completely independent.
Question 5 Short Answer
A line plot shows pencil lengths measured by 20 students. How would you use the plot to answer: (a) How many students measured exactly 15 cm? (b) Which length was most common?
Think about your answer, then reveal below.
Model answer: (a) Count the X marks stacked above 15 on the number line — that number is how many students recorded 15 cm. (b) Find the value with the tallest stack of X marks — that value appeared most often and is the most common length (the mode). The line plot makes both answers visible without any calculation: frequency questions are answered by counting X marks above a specific value, and comparison questions are answered by comparing the heights of stacks.
These two question types — frequency questions (how many for this value?) and comparison questions (which value is most/least common?) — are the primary analytical uses of a line plot. The visual layout is designed to make both fast to answer. Contrast this with a raw list of 20 numbers, where you would have to count and sort manually to answer either question.