4.A candy store has Snickers, Milky Way, Three Musketeers, Twix, and Rocky Road candy bars for sale. How many ways are there to select 16 candy bars to purchase?

Answer 1

It is C(16+5-1,5-1) = C(20,4) = 4845

One way to see why this formula is correct: we can consider having 4 walls to separate the 5 candies. C(20, 4) would be the number of ways that we could place the walls to generate each possible selection of the candies.