Math Problem Statement

Five cards are chosen at random from an ordinary deck to form a hand in poker. How many ways is it possible to choose at least 3 spades?

Solution

To solve this problem, we need to calculate the number of ways to choose at least 3 spades from a standard deck of 52 cards.

Step 1: Breakdown of the deck

  • A standard deck has 52 cards.
  • There are 13 spades in the deck.
  • There are 39 non-spade cards in the deck.

Step 2: Total number of ways to choose 5 cards from 52

The total number of ways to select 5 cards from 52 is given by the combination:

(525)=52×51×50×49×485×4×3×2×1=2,598,960\binom{52}{5} = \frac{52 \times 51 \times 50 \times 49 \times 48}{5 \times 4 \times 3 \times 2 \times 1} = 2,598,960

Step 3: Cases for choosing at least 3 spades

We need to consider the following cases:

  • 3 spades and 2 non-spades
  • 4 spades and 1 non-spade
  • 5 spades

Case 1: 3 spades and 2 non-spades

We can choose 3 spades from the 13 spades, and 2 non-spades from the 39 non-spades:

(133)×(392)=13×12×113×2×1×39×382×1=286×741=211,926\binom{13}{3} \times \binom{39}{2} = \frac{13 \times 12 \times 11}{3 \times 2 \times 1} \times \frac{39 \times 38}{2 \times 1} = 286 \times 741 = 211,926

Case 2: 4 spades and 1 non-spade

We can choose 4 spades from the 13 spades, and 1 non-spade from the 39 non-spades:

(134)×(391)=13×12×11×104×3×2×1×39=715×39=27,885\binom{13}{4} \times \binom{39}{1} = \frac{13 \times 12 \times 11 \times 10}{4 \times 3 \times 2 \times 1} \times 39 = 715 \times 39 = 27,885

Case 3: 5 spades

We can choose all 5 cards from the 13 spades:

(135)=13×12×11×10×95×4×3×2×1=1,287\binom{13}{5} = \frac{13 \times 12 \times 11 \times 10 \times 9}{5 \times 4 \times 3 \times 2 \times 1} = 1,287

Step 4: Total number of ways to choose at least 3 spades

Now, we add up all the cases:

211,926+27,885+1,287=241,098211,926 + 27,885 + 1,287 = 241,098

Conclusion:

There are 241,098 ways to choose at least 3 spades from a deck of 52 cards.

Would you like more details or have any questions?

Here are 5 related questions to explore:

  1. How many ways are there to choose exactly 4 spades in a poker hand?
  2. How many ways are there to choose a hand with no spades?
  3. What is the probability of drawing exactly 3 spades from a deck of 52 cards?
  4. How many ways can you choose 5 cards from the hearts suit only?
  5. How would the solution change if there were 54 cards in the deck, including jokers?

Tip: The combination formula (nr)\binom{n}{r} is crucial for counting selections without regard to order, and is extensively used in probability and combinatorics.

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Probability
Card Combinations

Formulas

Combination formula: \(\binom{n}{r} = \frac{n!}{r!(n-r)!}\)

Theorems

Combinatorics in card selection: Selecting specific suits from a deck

Suitable Grade Level

Grades 10-12