1. **State the problem:** We have marks out of 20 for 10 students: 10, 8, 15, 12, 7, 18, 10, 12, 14, 9. We need to prepare a frequency table showing each mark and the number of students who obtained it. Then, calculate the range of the marks. 2. **Prepare the frequency table:** - List the unique marks in ascending order: 7, 8, 9, 10, 12, 14, 15, 18. - Count how many times each mark appears: - 7 appears 1 time - 8 appears 1 time - 9 appears 1 time - 10 appears 2 times - 12 appears 2 times - 14 appears 1 time - 15 appears 1 time - 18 appears 1 time | Marks | Frequency | |-------|-----------| | 7 | 1 | | 8 | 1 | | 9 | 1 | | 10 | 2 | | 12 | 2 | | 14 | 1 | | 15 | 1 | | 18 | 1 | 3. **Calculate the range:** Range is the difference between the maximum and minimum marks. - Maximum mark: $18$ - Minimum mark: $7$ $$\text{Range} = 18 - 7 = 11$$ **Final answer:** The range of the marks is 11.