For the following questions answer them individually
The standard deviation of a distribution is 4. If each observation in that data is increased by 2, then the new standard deviation will be ______
There are 12 observations $$x_{1},x_{2}, ... ,x_{12}$$ and $$y_{1},y_{2}, ... ,y_{12}$$ of two variables x, y and $$d_{i} = x_{i} - y_{i}$$ for $$1 \leq i \leq 12$$. If $$\sum d_{i}^{2} = 65$$, then the coefficient of rank correlation is
Three numbers are chosen at random from 1 to 20. The probability that they are not consecutive, is
If 5 boys and 5 girls are allowed to sit in a row at random, then probability that no two girls sit adjacent to each other is
When two persons are chosen at random the probability that their dates of birth are not in the same calendar month is