The standard deviation σ of the first N natural numbers can be obtained using which one of the following formulae ?

A committee of three has to be chosen from a group of 4 men and…

Consider the following in respect of two events A and B : 1.P(A occurs but…

One bag contains 3 white and 2 black balls, another bag contains 5 white and…

A box has ten chits numbered 0, 1, 2, 3, …, 9. First, one chit…

If A and B are two events such that 2P(A) = 3P(B), where 0 <…