Events A and B associated with an experiment are said to be independent if 

Two sets each of $20$ observations, have the same standard deviation $'5'$. The first set has a mean $'17'$ and the second set mean $'22'$ then standard deviation of the combining the given two sets is

If A and B are two events such that P (A)=$\frac{1}{2}$ and P (B) = $\frac{2}{3}$ , then which of the

In a series of $100$ observations, half of them is equal to $p$ and remaining half equal to $-p$ if the standard deviation of these observations is $10$ then $|p|=$__   

The greatest value of a collection of data is $72$ and the least value is $28$. Then the coefficient of range is.