Question: a) Explain how to find a formula for the number of ways to select r objects from n objects when repetition is allowed and order does not matter.
b) How many ways are there to select a dozen objects from among objects of five different types if objects of the same type are indistinguishable?
c) How many ways are there to select a dozen objects from these five different types if there must be at least three objects of the first type?
d) How many ways are there to select a dozen objects from these five different types if there cannot be more than four objects of the first type?
e) How many ways are there to select a dozen objects from these five different types if there must be at least two objects of the first type, but no more than three objects of the second type?