Question 1: Calculate the midpoint of the class interval 10–20.

Answer: 15

Question 2: Plot the midpoint for the class interval 30–40 on the grid.

Answer: 35

Question 3: A frequency table shows class intervals 5–15, 15–25, 25–35. Calculate and plot their midpoints.

Answer: 10, 20, 30

Question 4: Identify the common mistake made when plotting midpoints if the points are not aligned with the class intervals.

Answer: Using class boundaries instead of midpoints

Question 5: Given class intervals 0–10, 10–20, 20–30, compute and correctly plot the midpoints.

Answer: 5, 15, 25

Question 6: Explain step-by-step how to find the midpoint of a class interval.

Answer: Add the lower and upper boundaries, then divide by 2

Question 7: A teacher plots midpoints but notices they are misaligned by 2 units. What is the likely mistake?

Answer: Incorrectly calculating midpoints or not adjusting for scale

Question 8: Construct a small frequency table with three class intervals, calculate their midpoints, and plot them accurately on the grid.

Answer: Example: 0–10, 10–20, 20–30; midpoints: 5, 15, 25

Question 9: A misconception is that midpoints are always at the center of the class interval. Is this true? Explain briefly.

Answer: No, midpoints are calculated as the average of class boundaries, which may not be visually at the center if class widths are uneven.

Question 10: Identify and correct the mistake: The class interval is 50–60, but the plotted midpoint is 55. The scale is 1 unit = 1 cm.

Answer: Midpoint is correct; mistake may be in plotting position or scale interpretation

Question 11: Using the grid, plot the midpoints of 12–22, 22–32, and 32–42. Then, connect the points to form a frequency polygon. Describe any errors to avoid.

Answer: Calculate each midpoint: 17, 27, 37. Ensure points are accurately placed at these values and connect smoothly. Avoid misaligning points or using wrong scale.