Final answer:
Tom's sales of discount cards should be represented using a discrete graph because the sales are counted in whole numbers, making the data quantitative discrete, similar to the counting of books.
Step-by-step explanation:
In the scenario where Tom is selling discount cards for a fundraiser, the representation of his sales is best done with a discrete graph. This is because the number of discount cards sold is counted in whole numbers and cannot take on fractional or decimal values. Discount cards are individual items that can only be sold in whole units, signifying that this scenario relates to quantitative discrete data.
For example, you cannot sell half a discount card, thus illustrating that the data does not fit the definition of a continuous graph where the data would be represented as a range of possibilities along a continuum. The quantitative discrete variable in this case is analogous to the number of books bought by students, as noted in Example 2.10, which is discrete since books are also counted.
Similar to a bar graph used for categorical data, as highlighted in exercise 35, a discrete graph such as a bar graph would be an appropriate representation for this type of data. This contrasts with a continuous graph, which is more suitable for data such as income levels or interest rates that can have a range of continuous values.