Answer:
a) 1680
<em>The number of ways to listen to four CDs from a selection of 8 CDs = 1680</em>
Step-by-step explanation:
<u><em>Explanation:-</em></u>
Given data the number of CD' s n = 8
<em>We have to selected '4' CD' s from total '8' CD's</em>
<em>By using permutations </em>
<em>The number of ways to listen to four CDs from a selection of 8 CDs.</em>
<em> = </em><em> </em>
<em> we know that </em>
<em>The number of ways to listen to four CDs from a selection of 8 CDs = 1680</em>