**11. **S.D(X) = 6 and S.D(Y) = 8. If X and Yare independent random variables, then S.D(X-Y) is:

- 2
- 10
- 14
- 100

Correct answer: (B)

10

10

**12. **The ratio of the standard deviation to the arithmetic mean expressed as a percentage is called:

- Coefficient of standard deviation
- Coefficient of skewness
- Coefficient of kurtosis
- Coefficient of variation

Correct answer: (D)

Coefficient of variation

Coefficient of variation

**13. **To compare the variation of two or more than two series, we use

- Combined standard deviation
- Corrected standard deviation
- Coefficient of variation
- Coefficient of skewness

Correct answer: (C)

Coefficient of variation

Coefficient of variation

**14. **If standard deviation of the values 2, 4, 6, 8 is 2.236, then standard deviation of the values 4, 8,12, 16 is:

- 0
- 4.472
- 4.236
- 2.236

Correct answer: (B)

4.472

4.472

**15. **The moments about mean are called:

- Raw moments
- Central moments
- Moments about origin
- All of the above

Correct answer: (B)

Central moments

Central moments

**16. **Moment ratios β1 and β2 are:

- Independent of origin and scale of measurement
- Expressed in original unit of the data
- Unit less quantities
- Both (a) and (c)

Correct answer: (C)

Unit less quantities

Unit less quantities

**17. **If the third moment about mean is zero, then the distribution is:

- Positively skewed
- Negatively skewed
- Symmetrical
- Mesokurtic

Correct answer: (C)

Symmetrical

Symmetrical

**18. **If mean=25, median=30 and standard deviation=15, the distribution will be:

- Symmetrical
- Positively skewed
- Negatively skewed
- Normal

Correct answer: (C)

Negatively skewed

Negatively skewed

**19. **In a symmetrical distribution, Q_{3} – Q_{1} = 20, median = 15. Q_{3} is equal to:

- 5
- 15
- 20
- 25

Correct answer: (D)

25

25

**20. **The degree of peaked ness or flatness of a unimodel distribution is called:

- Skewness
- Symmetry
- Dispersion
- Kurtosis

Correct answer: (D)

Kurtosis

Kurtosis