Alternative to tree diagrams? (1 Viewer)

[toprun91]

Hi,
This is more of a question of curiosity aimed for people who know. But is there an alternative to tree diagrams. How do people calculate the probability of events that require massive tree diagrams that cant be drawn

 

[mtsmahia]

tree diagrams!

use a computer

 

[toprun91]

what about tree diagrams the would branch out heaps of times. Ok what if for some unknown reason someone wanted to find the probability of rolling a two 5's and seven 6's when rolling nine dice?. Who can work that out? eh

 

[Brontecat]

tbh i can't see that question being asked in a hsc exam, so i wouldn't worry about doing the question too much

 

[toprun91]

Yer i am not worrying about it i only just wanted to know how people work out those situations in real life

 

[micuzzo]

Yer i am not worrying about it i only just wanted to know how people work out those situations in real life

binomial theorem.

and other complex formulae.

 

[Trebla]

Permutations, combinations and use of various probability distributions (e.g. binomial, geometric, multinomial etc)

 

[annabackwards]

Yeah, do 3U and you can use factorials XD

 

[toprun91]

thx everyone. if anyone has spare time and it isnt too hard post how you would solve my hypothetical question above using your 3 unit - 4 unit maths

 

[Aquawhite]

In just 2U mathematics (3U uses permutations and factorials) you will only ever get asked short probability questions and often they don't even require a tree diagram (because they very simple and can be done in the head).

At the most the tree will only be 4 times over E.g. something is drawn out three times.... then two options for win or lost on each.

 

[toprun91]

In just 2U mathematics (3U uses permutations and factorials) you will only ever get asked short probability questions and often they don't even require a tree diagram (because they very simple and can be done in the head).

At the most the tree will only be 4 times over E.g. something is drawn out three times.... then two options for win or lost on each.

I know, i am just curious to see how its done. I really wanted to do 3 unit but my school is very strict on getting in (you have to be invited) not sure if that's across all schools though. Anyway if anyone wants to show me i would be interested i just want to see if my hypothetical is feasible

 

[Aquawhite]

I know, i am just curious to see how its done. I really wanted to do 3 unit but my school is very strict on getting in (you have to be invited) not sure if that's across all schools though. Anyway if anyone wants to show me i would be interested i just want to see if my hypothetical is feasible

My school makes recommendations based your performance... not many people qualify for Extension Maths in my school though... they're under-educated in the field of maths >_> (damn school).

Although, most are encouraged to at least give it a go... see what they think.

 

[lychnobity]

what about tree diagrams the would branch out heaps of times. Ok what if for some unknown reason someone wanted to find the probability of rolling a two 5's and seven 6's when rolling nine dice?. Who can work that out? eh

I'm going to be epically wrong, but here goes:

9C2 x (1/6)² x 9C7 x (1/6)⁷ = 1/7776

 

[toprun91]

My school makes recommendations based your performance... not many people qualify for Extension Maths in my school though... they're under-educated in the field of maths >_> (damn school).

Although, most are encouraged to at least give it a go... see what they think.

I wish i was encouraged i was in a slightly too low maths class to make it into 2 unit so i had to complete all this extra work to get into 2 unit. I also had to get above 65% on the first test or else they would drop me. But i proved them wrong getting 94% and beating all but two 3 unit students. If i had my time over i would love to try harder and do 4 unit. Do you do 3 unit? if so can you show me the way to do the hypothetical probability question

 

[toprun91]

I'm going to be epically wrong, but here goes:

9C2 x (1/6)² x 9C7 x (1/6)⁷ = 1/7776

what does the c mean? how did you do it?

 

[lychnobity]

what does the c mean? how did you do it?

The C, (if you look on your calculator should be on top of some button as "nCr") is a function that calculates the number of ways of selecting r objects from a total of n objects.

Technically, what my working out should look like is:

⁹C₂ x (1/6)² x ⁹C₇ x (1/6)⁷ = 1/7776

Take ⁹C₂ for example, the 9 represents the total no. of objects (dice), but I wanted to choose 2, so ⁹C₂ calculates the number of ways I can choose 2 objects out of 9 objects.

The ⁹C₂ chooses any 2 dice to have a result of 5, and the (1/6)² is the probability of rolling 2 fives.

The same applies for the ⁹C₇, any 7 die to have a 6, and (1/6)⁷is the probability of rolling 7 sixes.

 

[danal353]

oh man the maths is hurting my mind...

 

[lychnobity]

oh man the maths is hurting my mind...

Care to verify my answer, Banana?

 

[danal353]

lol no i wouldn't because i can't bear to even read through it, let alone understand it

 

[Timothy.Siu]

yeah that looks right.