Dot Plots and Frequency Tables

Dot Plot

  • Definition: A dot plot is a number line with dots that display data.

Frequency

  • Definition: Frequency is the number of times a specific data point occurs.

Relative Frequency Table

  • Definition: Relative frequency represents the percentage of times each data point or group of data points occurs.

  • Formula: \text{Relative Frequency} = \frac{\text{Frequency}}{\text{Total}} = \text{%}

    • Example: If a data point appears 10 times out of a total of 100 data points, the relative frequency is 10100=10%\frac{10}{100} = 10\%.

Example Problem: Palma's Produce Sales

  • Scenario: Palma sells produce each week, and we are given the amount of produce sold over a period of time.

  • Data: 15, 19, 15, 16, 20, 16, 17, 20, 11, 12, 15, 20

  • Objective: Use a dot plot and frequency table to represent the data.

Steps

  1. Draw a Number Line:

    • Establish a number line with values ranging from 11 to 20.
    • Use a scale that covers the range from 10 to 20 to accommodate all data points.

  2. Plot the Data:

    • For each value in the data set, draw a dot on the number line corresponding to that value.

  3. Create a Frequency Table:

    • List each unique value from the number line in the table.

    • Count the number of dots above each value on the dot plot to determine the frequency of each value.

  • Frequency Table Example:
    • Value 11: 1 dot (Frequency: 1)
    • Value 12: 2 dots (Frequency: 2)
    • Value 15: 3 dots (Frequency: 3)
    • Value 16: 2 dots (Frequency: 2)
    • Value 17: 1 dot (Frequency: 1)
    • Value 19: 1 dot (Frequency: 1)
    • Value 20: 3 dots (Frequency: 3)