1. Find the mean of: 4, 6, 8, 10, 12.
- A8
- B10
- C40
- D6
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Answer: A) 8
Sum = 40, n = 5. Mean = = 8.
Class 9 Statistics — practice questions with answers
Statistics and Probability · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
2. Find the mean of: 35, 41, 39, 48, 37 (rounded to one decimal place).
- A36
- B80
- C44
- D40
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Answer: D) 40
Sum = 35+41+39+48+37 = 200. n = 5. Mean = 200/5 = 40.
3. For the data set 4, 7, 9, 11, what is the statistical term for the difference between the largest and smallest values?
- ARange
- BMean
- CMedian
- DMode
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Answer: A) Range
Range = largest value − smallest value = 11 − 4 = 7. The term asked is 'range'.
4. To find the class mark of the interval 50–60, Meera calculated 60 − 50 = 10. What is the correct class mark?
- A10
- B110
- C5
- D55
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Answer: D) 55
Meera found the class size, not the class mark. The class mark is the midpoint: = 55.
5. The data 5, 6, 7, 8, 9 has mean 7 and median 7. The value 9 is now replaced by 39. Which statement is TRUE?
- ABoth the mean and the median become 13
- BThe mean becomes 13 but the median stays 7
- CThe median becomes 13 but the mean stays 7
- DNeither the mean nor the median changes
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Answer: B) The mean becomes 13 but the median stays 7
New sum = 5 + 6 + 7 + 8 + 39 = 65, so the mean rises to = 13. The ordered data is 5, 6, 7, 8, 39 and the 3rd value is still 7, so the median is unchanged. This is why the median is preferred when a data set has an extreme value.
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