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

1. 2
2. 10
3. 14
4. 100
10

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

1. Coefficient of standard deviation
2. Coefficient of skewness
3. Coefficient of kurtosis
4. Coefficient of variation
Coefficient of variation

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

1. Combined standard deviation
2. Corrected standard deviation
3. Coefficient of variation
4. Coefficient of skewness
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:

1. 0
2. 4.472
3. 4.236
4. 2.236
4.472

15. The moments about mean are called:

1. Raw moments
2. Central moments
4. All of the above
Central moments

16. Moment ratios β1 and β2 are:

1. Independent of origin and scale of measurement
2. Expressed in original unit of the data
3. Unit less quantities
4. Both (a) and (c)
Unit less quantities

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

1. Positively skewed
2. Negatively skewed
3. Symmetrical
4. Mesokurtic
Symmetrical

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

1. Symmetrical
2. Positively skewed
3. Negatively skewed
4. Normal
Negatively skewed

19. In a symmetrical distribution, Q3 – Q1 = 20, median = 15. Q3 is equal to:

1. 5
2. 15
3. 20
4. 25