In how many ways can 3 exams can be conducted within a week, so that 2 examination are not scheduled on same day

Question

I think I m bit confused between permutation and combination please clarify that

Answer 1

You need to have $3$ exams within $7$ days with each exam having a different day

This is equivalent to choosing $3$ objects from $7$ objects.

This can be done in $\binom{7}{3}$

But if the order of the exams is important, then this can be done in

$\binom{7}{3}\cdot 3!$