Easy1 markMultiple Choice
AQA GCSE · Question 03 · Statistical Measures and Calculations
Which of these data lists is bi-modal and has the mean double the median?
Which of these data lists is bi-modal and has the mean double the median?
Answer options:
A.
4, 4, 6, 6, 30
B.
2, 4, 6, 6, 42
C.
0, 6, 6, 24, 24
D.
0, 0, 6, 6, 38
How to approach this question
1. Understand the definitions:
- **Bi-modal**: The data set has two modes (two values that appear most frequently).
- **Median**: The middle value when the data is in order.
- **Mean**: The sum of the values divided by the number of values.
2. Go through each option (A, B, C, D) and check both conditions.
3. **For option A:** Modes are 4 and 6 (bi-modal). Median is 6. Mean is (4+4+6+6+30)/5 = 10. 10 is not 2*6.
4. **For option B:** Mode is 6 (uni-modal). This option can be eliminated.
5. **For option C:** Modes are 6 and 24 (bi-modal). Median is 6. Mean is (0+6+6+24+24)/5 = 12. 12 is 2*6. This option satisfies both conditions.
6. **For option D:** Modes are 0 and 6 (bi-modal). Median is 6. Mean is (0+0+6+6+38)/5 = 10. 10 is not 2*6.
7. Conclude that C is the correct answer.
Full Answer
C.0, 6, 6, 24, 24✓ Correct
Let's check each option:
**A: 4, 4, 6, 6, 30**
- Modes: 4 and 6 (bi-modal).
- Median: 6.
- Mean: (4+4+6+6+30)/5 = 50/5 = 10.
- Is mean double the median? 10 is not 2 * 6.
**B: 2, 4, 6, 6, 42**
- Mode: 6 (not bi-modal).
**C: 0, 6, 6, 24, 24**
- Modes: 6 and 24 (bi-modal).
- Median: 6.
- Mean: (0+6+6+24+24)/5 = 60/5 = 12.
- Is mean double the median? Yes, 12 = 2 * 6.
**D: 0, 0, 6, 6, 38**
- Modes: 0 and 6 (bi-modal).
- Median: 6.
- Mean: (0+0+6+6+38)/5 = 50/5 = 10.
- Is mean double the median? 10 is not 2 * 6.
Therefore, C is the correct answer.
This question requires checking two statistical properties for each data set.
- **Bi-modal**: A data set is bi-modal if it has two values that occur with the same highest frequency.
- **Mean and Median**: The median is the middle value of an ordered dataset. The mean is the sum of all values divided by the count of values.
Let's analyze option **C: 0, 6, 6, 24, 24**
1. **Mode**: The numbers 6 and 24 both appear twice, which is more than any other number. So, it is bi-modal.
2. **Median**: The data is already in order. The middle value is the 3rd one, which is 6. So, the median is 6.
3. **Mean**: The sum is 0 + 6 + 6 + 24 + 24 = 60. There are 5 values. The mean is 60 / 5 = 12.
4. **Comparison**: The mean (12) is double the median (6).
Both conditions are met for option C.
Common mistakes
✗ Only checking one of the conditions (e.g., finding a bi-modal set but not checking the mean/median relationship).
✗ Calculation errors when finding the mean.
✗ Incorrectly identifying the median from an unordered list.
Practice the full AQA GCSE Statistics Higher Tier Paper 1
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