Cards

Cards

Posers and Puzzles

Cookies help us deliver our Services. By using our Services or clicking I agree, you agree to our use of cookies. Learn More.

r
CHAOS GHOST!!!

Elsewhere

Joined
29 Nov 02
Moves
17317
26 May 03

Given a standard, 52-card deck, how many combinations of five cards consist of at least three spades and exactly two cards of equal rank?

TANSTAAFL

Walking on sunshine

Joined
28 Jun 01
Moves
63101
27 May 03
1 edit

Originally posted by royalchicken
Given a standard, 52-card deck, how many combinations of five cards consist of at least three spades and exactly two cards of equal rank?
31086?

r
CHAOS GHOST!!!

Elsewhere

Joined
29 Nov 02
Moves
17317
27 May 03

Maybe, maybe not. What is your reasoning?

TANSTAAFL

Walking on sunshine

Joined
28 Jun 01
Moves
63101
27 May 03

Originally posted by royalchicken
Maybe, maybe not. What is your reasoning?
(1). # of 5-card combos wherein the pair are not one of the 3 spades = (# of distinct 3-spade combos) x (# of distinct non-spade pairs that dont match one of the spades + # of single spade pairs) = 66 x ((39 - 9) + (9x3)) = 3762

(2). # of combos wherein one of the pair is one of the 3 spades = (# of distinct 3-spade combos) x (# of possibilities for the 4th card for a given set of 3 spades) x (# of possibilities for the 5th card) = 66 x 9 x (48 - (2 (so that the 5th card doesn't match the pair) + 3 + 3 (so that the 5th card doesn't match either of the other two cards)) = 23760.

(1) + (2) = 27522.

(my original calculations didn't account for the possible matching of the pair with one of the spades)

r
CHAOS GHOST!!!

Elsewhere

Joined
29 Nov 02
Moves
17317
28 May 03
1 edit

I get 27522......Good job 😀! (My method was different though.)