Need explanation on the following questions:

5. An apartment building has the following distribution of apartments: 1 bedroom 2 bedroom 3 bedroom 1st floor w 0 2nd floor A 3rd floor 4 If an apartment is selected at random, what is the probability that it is on the 2nd floor or has 2 bedrooms? 6. Find the mean of the distribution shown. X 4 6 P(X) 0.38 0.62 7. A university has 10,000 students of which 65% are male and 35% are female. If a class of 30 students is chosen at random from the university population, find the mean and variance of the number of male students