To construct the 5-number summary from the given speed dating ratings, we first need to organize the data in ascending order:
Sorted Data: 1.0, 2.0, 2.5, 3.5, 4.5, 4.5, 5.0, 5.0, 5.0, 5.0, 5.0, 6.0, 6.5, 7.0, 7.0, 7.0, 8.0, 8.5, 9.5, 9.5
Five-Number Summary:
- Minimum: The smallest value in the dataset.
- First Quartile (Q1): The median of the first half of the dataset.
- Median (Q2): The median of the entire dataset.
- Third Quartile (Q3): The median of the second half of the dataset.
- Maximum: The largest value in the dataset.
Step-by-step calculation:
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Minimum: \( 1.0 \)
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Maximum: \( 9.5 \)
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Median (Q2):
- There are 20 data points, so the median is the average of the 10th and 11th values.
- 10th value: \( 5.0 \)
- 11th value: \( 5.0 \)
- \( \text{Median} = \frac{5.0 + 5.0}{2} = 5.0 \)
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First Quartile (Q1):
- The first half of the data includes the first 10 values: \( 1.0, 2.0, 2.5, 3.5, 4.5, 4.5, 5.0, 5.0, 5.0, 5.0 \).
- The median of this subset (5 values from either side) is the average of the 5th and 6th values:
- 5th value: \( 4.5 \)
- 6th value: \( 4.5 \)
- \( Q1 = \frac{4.5 + 4.5}{2} = 4.5 \)
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Third Quartile (Q3):
- The second half of the data includes the last 10 values: \( 5.0, 5.0, 6.0, 6.5, 7.0, 7.0, 7.0, 8.0, 8.5, 9.5 \).
- The median of this subset (5 values from either side) is the average of the 5th and 6th values:
- 5th value: \( 7.0 \)
- 6th value: \( 7.0 \)
- \( Q3 = \frac{7.0 + 7.0}{2} = 7.0 \)
5-Number Summary:
- Minimum: 1.0
- Q1: 4.5
- Median (Q2): 5.0
- Q3: 7.0
- Maximum: 9.5
Final Answer:
The 5-number summary is \( 1.0, 4.5, 5.0, 7.0, 9.5 \).