Lesson 2: Dot Plots and Histograms — Practice Questions

1. 1. A bar graph shows the number of books read by students in three classes. The vertical axis starts at 20 instead of 0. What problem does this create?

   • A. The categories will overlap
   • B. The differences between bars will appear larger than they really are
   • C. The bars will have no gaps between them
   • D. The axis labels will be incorrect

2. 2. Two stores sell the same item: Store X sells 105 units and Store Y sells 95 units. A bar graph starts its vertical axis at 90. How many units tall is Store X's bar on this graph?

   • A. 105
   • B. 95
   • C. 15
   • D. 10

3. 3. A bar graph displays favorite sports: Soccer (25 students), Basketball (20 students), Tennis (10 students). The vertical axis correctly starts at 0. The bar for Soccer is ___ units taller than the bar for Tennis.

4. 4. Which of the following is NOT a required feature of a valid bar graph?

   • A. A title
   • B. A vertical axis starting at 0
   • C. Gaps between the bars
   • D. Bars of equal height

5. 5. In a bar graph with the vertical axis starting at 60, Candidate A has a bar 9 units tall and Candidate B has a bar 3 units tall. What are their actual vote counts?

   • A. A: 69 votes, B: 63 votes
   • B. A: 9 votes, B: 3 votes
   • C. A: 60 votes, B: 60 votes
   • D. A: 54 votes, B: 57 votes

6. 6. The number of emails a manager received daily over two weeks is: 18, 25, 31, 16, 29, 22, 38, 19, 27, 33, 40, 24, 15, 36. What is the frequency for the interval 20-29 emails? ___

7. 7. A histogram shows the ages of visitors at a museum, with one bar representing the 30-39 age group. Can you find how many visitors are exactly 35 years old from the histogram alone?

   • A. Yes, by finding the midpoint of the bar's interval.
   • B. Yes, by dividing the height of the bar by 10.
   • C. No, because the histogram only shows the total number of visitors in the entire 30-39 age range.
   • D. No, because 35 is not the start or end of the interval.

8. 8. A baker tracks the number of cookies sold each day. Which of the following does the mean absolute deviation (MAD) of the sales data represent?

   • A. The total number of cookies sold.
   • B. The most common number of cookies sold in a day.
   • C. The range between the highest and lowest sales day.
   • D. The average distance of each day's sales from the mean number of sales.

9. 9. A histogram shows daily customer counts at a cafe. For 8 days there were 50-74 customers, for 15 days there were 75-99, and for 6 days there were 100-124. How many more days had 75-99 customers than 100-124 customers? ___