• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

Combinatorics Gurus helpppp (1 Viewer)

HeroWise

Active Member
Joined
Dec 8, 2017
Messages
353
Gender
Male
HSC
2020
For a poker hand (5 cards) what is the probability of getting a single pair

I got: (13C1)(4C2)(48C3)/52C5


But the solution in cambridge says other wise.

(13C1)(4C2)(12C3)4^3/52C5

I can understand where they are cming from But when i do 48C3 how am I over counting? This question is confusing me atm
 

fan96

617 pages
Joined
May 25, 2017
Messages
543
Location
NSW
Gender
Male
HSC
2018
Uni Grad
2024
does not exclude the possibility of having another pair.

i.e. the question (probably) asks for the probability of exactly one pair, but you calculated the probability of having at least one pair.

Doing (and then choosing suits afterwards) guarantees that all of the cards will have a different value.
 
Last edited:

HeroWise

Active Member
Joined
Dec 8, 2017
Messages
353
Gender
Male
HSC
2020
What how does that include more pairs? Lets say i picked 2 queens Thats set. I cant have another 1 or 2 queens cause it will give more than a pair. Thats why i have 48 which is 52-4

Does that mean I cant have 3 Aces included with the original 2 queens
 

fan96

617 pages
Joined
May 25, 2017
Messages
543
Location
NSW
Gender
Male
HSC
2018
Uni Grad
2024
What how does that include more pairs? Lets say i picked 2 queens Thats set. I cant have another 1 or 2 queens cause it will give more than a pair. Thats why i have 48 which is 52-4

Does that mean I cant have 3 Aces included with the original 2 queens
If your first pair were queens then your could choose 2 kings, 2 aces, 2 jacks etc. which would be more than 1 pair.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top