1. **Problem statement:**
We have a cumulative frequency diagram for 100 students recording the time $t$ (in minutes) taken to eat a pizza. We need to estimate:
(i) the median time,
(ii) the interquartile range (IQR),
(iii) the number of students taking more than 11 minutes.
2. **Understanding cumulative frequency:**
The cumulative frequency curve shows the total number of students who took up to a certain time to finish eating.
- Median corresponds to the time at which cumulative frequency is 50.
- Quartiles correspond to cumulative frequencies at 25 (Q1) and 75 (Q3).
3. **Estimating the median:**
From the graph, median is the time $t$ where cumulative frequency = 50.
- The curve reaches 50 students approximately at $t = 8$ minutes.
So, median $= 8$ minutes.
4. **Estimating the interquartile range (IQR):**
- Q1 is the time at cumulative frequency = 25.
- Q3 is the time at cumulative frequency = 75.
From the graph:
- Q1 is about $t = 6$ minutes.
- Q3 is about $t = 11$ minutes.
Therefore, $$\text{IQR} = Q3 - Q1 = 11 - 6 = 5 \text{ minutes}.$$
5. **Number of students taking more than 11 minutes:**
- At $t=11$ minutes, cumulative frequency is about 75.
- Total students = 100.
Number taking more than 11 minutes = $100 - 75 = 25$ students.
**Final answers:**
(i) Median = 8 minutes
(ii) Interquartile range = 5 minutes
(iii) Number of students taking more than 11 minutes = 25
Pizza Eating Time 3A6B0A
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