Question

How many ways can eight letters be arranged into groups of five where order matters and the first two letters are already chosen ?

A 100
B 120
C 240
D 720

Answer 1

120

Explanation:

Think about the eight letters A B C D E F G H, if A and B (or any two letters) are already chosen then you want to know how many ways 6 letters can fill 3 spaces when order matters, in other words the letters F G H are considered 1 outcome with the first two letters and G F H is considered another individual outcome with the first two letters. If order didn't matter then F G H and G F H with the first two letters would be considered only one outcome.