Answer:
A) there are 270.725 total of poker hands
B) there are 14.950 possible black flushes
C) the probability of being dealt a black flush is 0.0552220
Explanation:
Combinations gives the number of ways a subset of r elements can be chosen out of a set of n elements. Let's use the "n choose r" formula:
![nCr=((n!))/((r!(n-r)!))](https://img.qammunity.org/2020/formulas/mathematics/college/i3tj9mx2ctalro2n9xcxhugd6vzkcfd5es.png)
A) the total number of combinations of 4 cards chosen from the deck of 52 cards:
n = 52
r = 4
![nCr= (52!)/((4!(52-4)!)) = (52!)/(4!(48!)) =(52*51*50*49*48!)/(1*2*3*4(48!))](https://img.qammunity.org/2020/formulas/mathematics/college/pep6thoeuwmrz5sx9iqrvv03doz43xs5ga.png)
The 48! terms cancel
![nCr=(52*51*50*49)/(1*2*3*4) = (6.497.400)/(24) =270.725](https://img.qammunity.org/2020/formulas/mathematics/college/a516gz6stgijrglt8xmfehedlnq92dfng2.png)
B) Number of possible black flushes:
There are 26 black cards (spades and clubs)
n=26
r=4
![nCr=(26!)/(4!(22!))= (26*25*24*23*22!)/(1*2*3*4(22!)) =(358.800)/(24) \\\\nCr= 14.950](https://img.qammunity.org/2020/formulas/mathematics/college/yqr0l0637wahy7geqf56basp7kimy70yrq.png)
C) Probability of being dealt a black flush
Simply divide the result of B) over A)
![P=(14.950)/(270.725) = 0.0552220](https://img.qammunity.org/2020/formulas/mathematics/college/37swlzkofps4qor4gfokgtcriq3nmfzlez.png)