Determine the number of 5-card combinations out of a deck of 52 cards if each selection of 5 cards has exactly one king.
778320
Explanation
This question is similar to Question 6 in the Miscellaneous Exercise which asks for exactly one ace. The same logic applies: we use the multiplication principle by first selecting 1 king from 4 kings, then selecting 4 non-king cards from the remaining 48 cards. The formula for combinations nCr is used as shown in Example 19.
Solution Steps
Step 1: A deck has 52 cards with 4 kings. We need exactly one king in our selection of 5 cards.
Step 2: Number of ways to select 1 king from 4 kings = ⁴C₁ = 4!/(1! × 3!) = 4
Step 3: Number of ways to select remaining 4 cards from 48 non-king cards = ⁴⁸C₄ = 48!/(4! × 44!)
Step 4: Calculating ⁴⁸C₄ = ( × )/( × ) = 194580
Step 5: By multiplication principle, total combinations = ⁴C₁ × ⁴⁸C₄ = = 778320