Let's solve each question in order, starting with the median house value:
1. Median Value of the Houses
The values and their counts are as follows:
- $150,000: 2 Houses
- $220,000: 4 Houses
- $490,000: 3 Houses
- $540,000: 2 Houses
- $800,000: 5 Houses
- $975,000: 2 Houses
To find the median, we need to list out all values in order:
- $150,000, $150,000 (2)
- $220,000, $220,000, $220,000, $220,000 (4)
- $490,000, $490,000, $490,000 (3)
- $540,000, $540,000 (2)
- $800,000, $800,000, $800,000, $800,000, $800,000 (5)
- $975,000, $975,000 (2)
Putting them in order:
- $150,000, $150,000, $220,000, $220,000, $220,000, $220,000, $490,000, $490,000, $490,000, $540,000, $540,000, $800,000, $800,000, $800,000, $800,000, $800,000, $975,000, $975,000
Total number of houses: 2 + 4 + 3 + 2 + 5 + 2 = 18 houses.
The median is the average of the 9th and 10th numbers in this ordered list:
- 9th number: $490,000
- 10th number: $540,000
Median = ($490,000 + $540,000) / 2 = $515,000
2. Mean Test Scores Increase
We will calculate the mean score for each student and the increase upon receiving a perfect score (100).
-
Dana:
- Mean = (68 + 74 + 83 + 80 + 81 + 82) / 6 = 74.67 (approx.)
- New mean = (74.67 * 6 + 100) / 7 = 81.14 (approx.)
- Increase = 81.14 - 74.67 = 6.47
-
Theo:
- Mean = (84 + 88 + 81 + 85 + 77 + 76) / 6 = 82.83 (approx.)
- New mean = (82.83 * 6 + 100) / 7 = 86.04 (approx.)
- Increase = 86.04 - 82.83 = 3.21
-
Jose:
- Mean = (91 + 93 + 97 + 96 + 96 + 96) / 6 = 94.83 (approx.)
- New mean = (94.83 * 6 + 100) / 7 = 96.69 (approx.)
- Increase = 96.69 - 94.83 = 1.86
-
Ara:
- Mean = (100 + 98 + 99 + 97 + 100 + 100) / 6 = 99.67 (approx.)
- New mean = (99.67 * 6 + 100) / 7 = 99.86 (approx.)
- Increase = 99.86 - 99.67 = 0.19
The student with the most significant increase is Dana, with an increase of approximately 6.47.
3. Range of Roller Coaster Speeds
Europe (from the stem-and-leaf plot):
- Minimum speed = 74 mph
- Maximum speed = 111 mph
Range = Max - Min = 111 - 74 = 37 mph
North America (from the table):
Speeds: 85, 90, 92, 93, 95, 100, 120, 128
- Minimum speed = 85 mph
- Maximum speed = 128 mph
Range = Max - Min = 128 - 85 = 43 mph
Summary of Ranges:
- Europe: 37 mph
- North America: 43 mph
4. Mean Daily High Temperatures
Sample 1:
Mean = (78 + 82 + 85 + 87 + 90 + 85 + 79 + 86 + 91 + 88) / 10 = 84.6°
Sample 2:
Mean = (81 + 79 + 80 + 86 + 89 + 92 + 82 + 88 + 84 + 87) / 10 = 84.8°
Difference:
Difference = 84.8 - 84.6 = 0.2°
5. Percentage of Bird Owners
In Sample 1:
- Total bird owners = 8
- Percentage = (8/100) * 100 = 8%
In Sample 2:
- Total bird owners = 12
- Percentage = (12/100) * 100 = 12%
Combined % across both samples:
- Combined Total = 8 + 12 = 20
- Total students = 100 + 100 = 200
Total percentage of students owning a bird = (20/200) * 100 = 10%.
Final Answers:
- Median House Value: $515,000
- Mean Increase: Dana's mean increases the most.
- Range for Europe: 37 mph, Range for North America: 43 mph.
- Mean temperatures differences: 0.2°.
- Percentage owning a bird: 10%.