Question: 1. In how many ways can 6 people be seated in a circle of 6 chairs? Only relative positions in the circle an be distinguished.
2. In how many ways can first, second, and third prize in a pie-baking contest be given to 15 contestants?
a. Stock designations on an exchange are limited to 3 letters. How many different designations are there?
b. How many different designations are there if letters cannot be repeated?