- AMean 40, SD 10
- BMean 50, SD 10
- CMean 40, SD 8
- DMean 30, SD 7.5
Step-by-Step Solution
Adding 10 leaves the SD (σ) unchanged. and , so and . (Mean 50 is the value after adding 10.)
Answer: A) Mean 40, SD 10
A data set has a coefficient of variation of 25%. When 10 is added to every value, the coefficient of variation becomes 20%. What are the original mean and SD?
Competition practiceStatistics
Master this topic in 30 minutes a day.
Don't just memorise the answer — build a daily practice habit.
Practice 5 Similar Questions Free →All Statistics practice questions
More Statistics practice
Eighteen observations have mean 7 and standard deviation 4. The observation 12 is then…Ten observations have variance 9. Each is multiplied by 2 and then 3 is added; after…For n observations, Σ(x − 5) = 20 and Σ(x − 5)² = 160, and their mean is 6. Find n and…Two numbers have mean 9 and standard deviation 3. A third number, 15, is added to them.…In a survey of 50 families, the number of children per family was: 0 children – 6…