Question

Which statement is true?
You can use both permutations and combinations when order matters.
You can use permutations when order matters and use combinations when order doesn’t matter.
You can use permutations when order doesn’t matter and use combinations when order matters.
You can use permutations and combinations when order doesn’t matter.

Answer 1

You can use permutations when order matters and use combinations when order doesn’t matter.

Reason: permutations count ordered arrangements (e.g., seating people in a row: P(n,k) = n!/(n−k)!), while combinations count unordered selections (e.g., choosing a committee: C(n,k) = n!/(k!(n−k)!)).