GraphModerate1 mark
7(b)
The table shows the distribution of the scores obtained by 160 shooters in a shooting competition. Use a graph sheet and draw an ogive for the distribution. (Take 2 cm = 10 scores on the X-axis and 2 cm = 20 shooters on the Y-axis). Use your graph to estimate the following:
The median.
Topic: Reflection and plotting
Previous-year question practice database
Answer
Solution diagram
Exam answer
| Scores | f | Cumulative frequency |
|---|---|---|
| 0–10 | 9 | 9 |
| 10–20 | 13 | 22 |
| 20–30 | 20 | 42 |
| 30–40 | 26 | 68 |
| 40–50 | 30 | 98 |
| 50–60 | 22 | 120 |
| 60–70 | 15 | 135 |
| 70–80 | 10 | 145 |
| 80–90 | 8 | 153 |
| 90–100 | 7 | 160 |
| Total | 160 |
N = 160. Median position = N/2 = 80.
From the ogive, the score corresponding to c.f. 80 is approximately 43.
Answer: Median ≈ 43.
Explanation
Prepare the cumulative-frequency table, plot the upper class limits against c.f., then read the x-value at c.f. 80.