16.
Which two of the following statements are true?
(1) Skewness studies the flatness or peakedness of the distribution
(2) A positively skewed distribution curve is stretched more to the right than to the left
(3) On the basis of empirical relationship between mean, mode and median for moderately asymmetrical distribution, Karl Pearson's coefficient of skewness can be measured by 3 (Mean-Median) divided by Standard Deviation
(4) If mean > mode, the distribution is positively skewed
Choose the correct option from those below:

17.
Which one of the following formulae is used to calculate the standard error of coefficient of correlation between 25 paired observations of a sample?

20.
With reference to the time series analysis which of the following statement is/are correct?
(1) Time series analysis is not used when the values are constant
(2) Time series analysis is not used when the values are in the form of a function
Select the correct answer using the options given below