Question: A game consists of choosing and listing, in order, three numbers from the integers 1, 2... 20.
(a) How many different choices are there?
(b) What percentage of these begins with the number 4? Would this answer change if the first number is 17 instead of 4?
(c) What percentage of these choices ends with the number 9? Would this number be the same if the last number were 11 instead of 9?
(d) How many choices are there if the first number must be 3 and the last number 15?