• Best of luck to the class of 2024 for their HSC exams. You got this!
    Let us know your thoughts on the HSC exams here
  • YOU can help the next generation of students in the community!
    Share your trial papers and notes on our Notes & Resources page
MedVision ad

Probability Question (1 Viewer)

Stabilo123

Member
Joined
Nov 6, 2011
Messages
30
Gender
Male
HSC
2012
At Tristan's school, all students are required to study 3 different electives.
They must choose one language: Greek, Arabic or French,
one Social Science: History, Geography, Legal Studies or Business,
and one Technical subject: Computing, Design or Technology.
How many different elective combinations are there available

I thought it would be 3 x 4 x 3 = 36 but the answer is 12 according to the answer at the back of the textbook?
 

CrackerMo

Member
Joined
Jul 24, 2011
Messages
77
Gender
Male
HSC
N/A
Language and social science combination is already 12, so it can't be the right answer...
 

zeebobDD

Member
Joined
Oct 23, 2011
Messages
414
Gender
Male
HSC
2012
hmm it should be 36, ans at the back of the book arent always correct.
 

Kat92

Active Member
Joined
Oct 29, 2008
Messages
831
Gender
Female
HSC
2009
I would do a tree diagram with language as the first branch, then the social sciences and finally technology.

When complete it equals 36.


Also you could:

Convert to improper fractions and multiply out to get 36.


I can't really see how you would get 12?? As I agree with CrackerMo language and social science is already at 12. Unless you divide because the student is only required to have 3 electives
 

RealiseNothing

what is that?It is Cowpea
Joined
Jul 10, 2011
Messages
4,591
Location
Sydney
Gender
Male
HSC
2013
I would do a tree diagram with language as the first branch, then the social sciences and finally technology.

When complete it equals 36.


Also you could:

Convert to improper fractions and multiply out to get 36.

I can't really see how you would get 12?? As I agree with CrackerMo language and social science is already at 12. Unless you divide because the student is only required to have 3 electives
Why would you need to convert to improper fractions? Just multiply the options together in each category: 3x4x3 = 36
 

Kat92

Active Member
Joined
Oct 29, 2008
Messages
831
Gender
Female
HSC
2009
It depends on how particular teachers require it. My teacher required us to use fractions most of the time for each item out of the total.

Also because of the P(Event) formula I think this was the case why he was strict on it.

Personally I prefer just to multiply as well! Especially when it is a question like this one. :D
 

Eduard_Khil

CASIO fx-82ES PLUS
Joined
Feb 7, 2012
Messages
157
Location
NSW
Gender
Male
HSC
N/A
This question highlights many notions; thus several complications arise. In my opinion, several variables affect the validity of the answer. In simpler terms, the answer in the textbook should be one that is concurrent to the question. Therefore, to address this situation you must: firstly check that the question under the investigation and the answer upon your fore-mentioned question relates back to your chosen question, that is, (note, I will use some examples that may help you in your understanding of this post) to check the answer for Question 1, you must look up the Answer 1, your problem may be thus. If however your question does not match the answer, check that the exercise also corresponds to the exercise upon your completion. If this is not the case, fear not, there are other ways to check the validity of the question and answer.

However, I must address the notions of probability laws, by-which your answer may be affected by; The Monte Carlo fallacy, on that:
The Gambler's fallacy, also known as the Monte Carlo fallacy (because its most famous example happened in a Monte Carlo Casino in 1913),[1][2] and also referred to as the fallacy of the maturity of chances, is the belief that if deviations from expected behaviour are observed in repeated independent trials of some random process, future deviations in the opposite direction are then more likely.

thus, the aboveforementioned responses may not be right, due to the numerical influences in which they were taken, this corresponds to something known as the Bandwagon effect bywhich influences to an individual's answer may be influenced by the sheer number of other, often wrong answers. Another factor influencing the answer may be:

The proposition in probability theory known as the law of total expectation, the law of iterated expectations, Adam's law, the tower rule, the smoothing theorem, among other names, states that if X is an integrable random variable (i.e., a random variable satisfying E( | X | ) < ∞) and Y is any random variable, not necessarily integrable, on the same probability space, then

i.e., the expected value of the conditional expected value of X given Y is the same as the expected value of X.
--------------------------
If, after you have read, checked (and rechecked, mind you; as you should know now that the Law of total expectations, Monte Carlo fallacy and Bandwagon effect may influence your ability to make valid calculations). You may find that the answer in your book was in fact correct therefore, following these above steps, you would of proved the textbook answers wrong, and then proceed to sue the producers for both misleading information and wasting your time.

Thank you for reading my post
 

math man

Member
Joined
Sep 19, 2009
Messages
503
Location
Sydney
Gender
Male
HSC
N/A
there is no doubt the answer is 36, if i apply simply combinations (i know general doesnt do it but who cares)
there are 3C1 ways to pick a language
4C1 ways to pick a socail science
and 3C1 ways to pick a tech thingy.
Now because i want a language and a social science and a tech thingy then
toal ways = (3C1)(4C1)(3C1)=3x4x3=36
 

Eduard_Khil

CASIO fx-82ES PLUS
Joined
Feb 7, 2012
Messages
157
Location
NSW
Gender
Male
HSC
N/A
there is no doubt the answer is 36, if i apply simply combinations (i know general doesnt do it but who cares)
there are 3C1 ways to pick a language
4C1 ways to pick a socail science
and 3C1 ways to pick a tech thingy.
Now because i want a language and a social science and a tech thingy then
toal ways = (3C1)(4C1)(3C1)=3x4x3=36
under the current circumstances, I am inclined to disagree on your replying to this thread... As shown above I have included a detailed analysis on how the answer may be checked. This means any other attempts to answer these questions are futile. And may or may not be ridiculed by others in an appropriate manner. Since I have already answered this proposition, I feel that it would be of great necessity to lock this thread. In order to prevent further trolling within this thread, which may lead to more confusion as, I previously mentioned the "Band wagon" effect. Good day.
 

math man

Member
Joined
Sep 19, 2009
Messages
503
Location
Sydney
Gender
Male
HSC
N/A
Since I have already answered this proposition, I feel that it would be of great necessity to lock this thread. In order to prevent further trolling within this thread, which may lead to more confusion as, I previously mentioned the "Band wagon" effect.
I don't believe in trolls.
 

Eduard_Khil

CASIO fx-82ES PLUS
Joined
Feb 7, 2012
Messages
157
Location
NSW
Gender
Male
HSC
N/A
Whether or not you believe in trolls, doesn't matter, you see, this is a probability question and you clearly are not answering the purpose of this thread. Which is why I suggested that the thread should be locked, in order to prevent people from discussing matters that do not relate to the proposition of this thread. As previously stated before, multiple answers can confuse readers, the purpose of the thread has already been answered by me. Therefore talking about Scandinavian mythology on whether or not trolls exist is not a valid response.
 

Timske

Sequential
Joined
Nov 23, 2011
Messages
794
Gender
Male
HSC
2012
Uni Grad
2016
Whether or not you believe in trolls, doesn't matter, you see, this is a probability question and you clearly are not answering the purpose of this thread. Which is why I suggested that the thread should be locked, in order to prevent people from discussing matters that do not relate to the proposition of this thread. As previously stated before, multiple answers can confuse readers, the purpose of the thread has already been answered by me. Therefore talking about Scandinavian mythology on whether or not trolls exist is not a valid response.
Atar: 9001
 

Eduard_Khil

CASIO fx-82ES PLUS
Joined
Feb 7, 2012
Messages
157
Location
NSW
Gender
Male
HSC
N/A
Congratulations you have identified my forum signature.
I salute you.
 

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

Top