Question

What are the number of ways of selecting 7 files out of 14 distinct files if one is always selected?

Answer 1

one file is already selected ,

The number of ways of selecting 1 file from 14 =14

So now  we need to select 6 files from 13 files.

The number of ways of doing this = 13C6

=13!/6!7!

=1716

So the total number of selecting 7 files out of 14 distinct files in which 1 file is always selected = 14×1716

=24024

Answer 2

Answer:

Given one is always selected,the number of ways of selecting that one file always is ¹c1=1

remaining files can be selected in ¹³c6

total number of ways=¹³c6*¹c1