counting with identical items
summary
the content provides a comprehensive guide on how to approach counting problems on the gre, specifically focusing on arrangements involving identical items.
- introduces the concept of counting arrangements with identical items, highlighting the need for a special approach.
- explains the process of calculating arrangements using factorials, with examples including arranging books on a shelf.
- presents the 'mississippi rule' for cases with multiple sets of identical items, offering a formula for calculating arrangements.
- provides a practice problem to apply the concepts learned, reinforcing the method of dividing the total factorial by the factorials of identical items.
- emphasizes the importance of listing and counting as a strategy to understand and solve counting problems.
chapters
00:01
introduction to counting identical items
00:28
calculating arrangements with factorials
03:16
the mississippi rule
04:31
practice problem and summary
