This cumulative frequency diagram shows information about the height, in metres, of each of 100 students. Use it to find the median height.

The x-axis represents Time in hours, and the y-axis represents Temperature in degrees Celsius.

a. 7 Hours, b. 19 Hours, c. 17 Hours, d. 21 Hours.

• At 19 hours, the temperature is 50 degrees Celsius (Point G).
• At 17 hours, the temperature is 60 degrees Celsius (Point F).
• At 21 hours, the temperature is 40 degrees Celsius (Point H). This is the last recorded time and also the lowest temperature shown on the graph.

The correct answer is d.

For a cumulative frequency diagram with a total of 100 students, the median corresponds to the cumulative frequency of $\frac{100}{2} = 50$.

• The y-axis has major grid lines every 20 units, with 4 smaller grid lines between them. This means each small grid line represents $20/5 = 4$ units. So, 50 is exactly halfway between 40 and 60.
• The x-axis has major grid lines every 0.1 m (e.g., from 1.6 to 1.7), with 4 smaller grid lines between them. This means each small grid line represents $0.1/5 = 0.02$ m.
• Tracing from $y=50$ to the curve and then down to the x-axis, the line intersects the x-axis at the second small grid line after 1.6 m.
• Therefore, the median height is $1.6 + (2 \times 0.02) = 1.6 + 0.04 = 1.64$ m.

The correct answer is c.