Permutations & Combinations

Front

What is a permutation?

Back

A permutation is an arrangement of objects in a specific order. The order of arrangement matters.

Front

What is a combination?

Back

A combination is a selection of objects where the order does not matter.

Front

How many ways can a club select a president, vice president, and a secretary from a group of 5 people?

Back

60

Front

What does the P stand for in nPr?

Back

Permutations

Front

Calculate 20P2.

Back

380

Front

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

Back

nPr = n! / (n - r)! where n is the total number of objects and r is the number of objects to arrange.

Front

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

Back

nCr = n! / [r!(n - r)!] where n is the total number of objects and r is the number of objects to choose.

Front

How many different ways can first, second, and third prize be awarded among 6 different organizations?

Back

120

Front

If a student can choose 3 books from a shelf of 10, how many combinations are possible?

Back

120 (10C3 = 10! / [3!(10 - 3)!])

Front

What is the difference between permutations and combinations?

Back

Permutations consider the order of selection, while combinations do not.