1. **Problem statement:**
Daisy recorded her 50 homework marks with frequencies given for each mark from 15 to 20. We need to find:
(i) The range
(ii) The mode
(iii) The median
(iv) The mean
2. **Given data:**
Homework marks: 15, 16, 17, 18, 19, 20
Frequencies: 1, 3, 19, 11, 10, 6
3. **(i) Range:**
The range is the difference between the highest and lowest marks.
$$\text{Range} = 20 - 15 = 5$$
4. **(ii) Mode:**
The mode is the mark with the highest frequency.
Frequencies: 1, 3, 19, 11, 10, 6
Highest frequency is 19 at mark 17.
So, $$\text{Mode} = 17$$
5. **(iii) Median:**
The median is the middle value when all marks are arranged in order.
Total frequency = 1 + 3 + 19 + 11 + 10 + 6 = 50
Median position = $$\frac{50 + 1}{2} = 25.5$$th value
Cumulative frequencies:
- Up to 15: 1
- Up to 16: 1 + 3 = 4
- Up to 17: 4 + 19 = 23
- Up to 18: 23 + 11 = 34
The 25.5th value lies in the 18 marks group (since 23 < 25.5 ≤ 34).
So, $$\text{Median} = 18$$
6. **(iv) Mean:**
Mean is the sum of all marks times their frequencies divided by total frequency.
Calculate total sum:
$$\text{Sum} = 15 \times 1 + 16 \times 3 + 17 \times 19 + 18 \times 11 + 19 \times 10 + 20 \times 6$$
$$= 15 + 48 + 323 + 198 + 190 + 120 = 894$$
Mean:
$$\text{Mean} = \frac{894}{50} = 17.88$$
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**Summary:**
(i) Range = 5
(ii) Mode = 17
(iii) Median = 18
(iv) Mean = 17.88
Homework Marks Bcb2Ca
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