Consider a room of 20 people suppose it is equally likely

Question

1. Consider a room of 20 people. Suppose it is equally likely that there a person is male or female. A formula for the pdf of X= the number of women in the room
2. Consider a box of 20 black and white stone, with 12 of the stones being white. Suppose one selects 8 stones from the box. a formula for the pdf of X=the number of black stones from the 8 stones
3. How are the mean of a data set and the mean of a discrete random variable related?
4. Consider a device comprised of 20 components. there is a 10% chance that any one components will break. A formula for the P.D.F of the number of components(out of 20) that will not break
5. Referring to the above problem, compute the probability that 8 components will not break.
6. Reffering to the above problem, compute the average number of components that will not break