### Concept (1)

In statistics, in order to find the number of possible arrangements of a set of objects, we use a concept called permutations. There are methods for calculating permutations, and it's important to understand the difference between a set with and without repetition. Other important concepts that can apply to situations like permutations are the fundamental counting principal and basic probability.

### Sample Problems (4)

Need help with "Permutations" problems? Watch expert teachers solve similar problems to develop your skills.

7 runners in a race, how many different ways can they medal?

###### Problem 1
How to calculate the number of different ways runners can place.

How many distinct ways are there to arrange the letters in mom?

###### Problem 2
How to calculate the number of distinct permutations of a word.

An ATM pin consists of four numbers. How many pins if

a) repetition is allowed
b) repetition is not allowed
###### Problem 3
To calculate how many different PIN numbers there can be for an ATM card with and without repetition.

How many ways can 5 guys and 4 girls be arranged so that guys and girls must alternate?

###### Problem 4
How to calculate the number of different ways to line up objects when alternation is required.