NDA | Mathematics | Frequency Distribution

In a study of two groups, the following results were obtained:

Which of the following statements is correct?

Consider the following statements in respect of class intervals of grouped frequency distribution :

1) Class intervals need not be mutually exclusive.

2) Class intervals should be exhaustive.

3) Class intervals need not be of equal width.

Which of the above statements are correct?

The correlation coefficient between two variables X and Y is found to be 0·6. All the observations on X and Y are transformed using the transformations U = 2 - 3X and
V = 4 Y + 1. The correlation coefficient between the transformed variables U and V will be

The regression lines will be perpendicular to each other if the coefficient of correlation r is equal to

The variance of 20 observations is 5. If each observation is multiplied by 2, then what is the new variance of the resulting observations?