A club elects the president, vice-president, and secretary-treasurer. How many sets of officers are possible if there are 15 members as well as any member can be elected to each position? No person can hold more than one office.
How many ways can 5 people, A, B, C, D and E, sita in a row at the concer hall if A and B should sit together?
How many distinct arrangements can be formed from all letters of "statistics"?