Permutations and Combinations

Front

What is a permutation?

Back

An arrangement of objects in a specific order.

Front

What is a combination?

Back

A selection of objects without regard to the order.

Front

How many ways can you arrange 3 books on a shelf?

Back

6 (3! = 3 × 2 × 1 = 6).

Front

What is the formula for permutations of n objects taken r at a time?

Back

nPr = n! / (n - r)!.

Front

What is the formula for combinations of n objects taken r at a time?

Back

nCr = n! / [r!(n - r)!].

Front

If you have 4 different fruits, how many ways can you choose 2?

Back

6 (4C2 = 4! / [2!(4 - 2)!] = 6).

Front

How many different 3-digit numbers can be formed using the digits 1, 2, 3 without repetition?

Back

6 (3! = 6).

Front

What is the total number of routes from Ponder to Saginaw if there are 6 roads from Ponder to Justin, 2 from Justin to Halslet, and 3 from Haslet to Saginaw?

Back

36 (6 × 2 × 3 = 36).

Front

What is the number of permutations of n different objects taken r at a time with repetition?

Back

n^r.

Front

In how many ways can a president, vice-president, treasurer, historian, and secretary be selected from 24 members?

Back

5,100,480.