Probability

JW91

I'm doing HL Maths and I'm just wondering what all you fellow honours students think of probability?

Am I the only one who finds it ridiculously easy? Almost all of my friends say they find it tricky but I find it to be by far the most straight forward thing on the Maths course.

What do you all think of it? Will you be doing the Probability questions on monday?

challengemaster

I love it - It's all about rational thinking and just actually using your head instead of just remembering equations and hardcore maths where you just bash it out. Different style of thinking which is why a lot of people don't like it - they've never been introduced to this kind of thing before - people don't like change

Dubs

it can be tricky at times but defo the nicest question on paper 2

LivingDeadGirl

Found it ok but haven't revised it in ages. Thinking of doing loads of work on it tomorrow and doing those 2 questions instead of trigonometry(I'm terrible at it). If paper 2 goes badly there's a chance I could fail.....

JW91

I'd say to be honest you won't need to do a terrible amount of revision for it. Once you practise a few of them it'll come back to you.

It's a pretty easy section once you can think rationally

Pygmalion

Probability is handy in that you can't really study for it and it takes pretty much no time to do, I can go in and answer both questions at the start, leaving me with a good idea of how long I can spend on the other 4 questions.

The problem is, it's very hard to check your answers, at most you can look at the fraction you end up with and decide if it looks right, but for any non-trivial questions you can get an answer without having any idea if you got full, most, or attempt marks on it.
Although if it looks right and you look over it a second time then you're probably right, save for misunderstanding the question.

I'd prefer to answer at least one extra question if time permits so I'm not relying on both the probability questions for that reason.

KnifeWRENCH

Most people either love probability or can't stand it. There doesn't seem to be any middle ground.

I fell into the former category. Questions 6 and 7 on Paper 2 were by far my favourite questions on the whole exam. Of course that includes statistics aswell, and the statistics part of the course is ridiculously short.

There was only one other person in my year who did HL maths - she was excellent at maths and was better than me at every section of the course except for probability. (Although she hated vectors too for some reason)

Fringe

I used to hate it because we did it initially using the fractions way. Then we used the nCr way which is so much better and I find probability pretty easy.

Pygmalion

Fringe wrote: »

I used to hate it because we did it initially using the fractions way. Then we used the nCr way which is so much better and I find probability pretty easy.

I can't do it at all using nCr, I understand exactly why it works if explained, and if I saw someone do it the nCr way I'd understand exactly how they're doing it, but I really just can't grasp it myself.

Luckily I seem to do ok with the fractions way, it takes longer but it's still the quickest 2 questions on the exam (although statistics slows it down a bit)

Col Man

Oh Prob is savage. Do any of you guys do Question 9 as well? It's too good, far easier than Q8.

Pygmalion

Col Man wrote: »

Oh Prob is savage. Do any of you guys do Question 9 as well? It's too good, far easier than Q8.

Heresy!

Col Man

Lol are you having a laugh mate? Our whole class has no idea why only like 5% or less people do Q9. It's pretty much the shortest question on the paper, and it's an easy 50 in comparison to the rest.

Q8 could be worse though, not a whole lot to learn for it.

Pygmalion

Col Man wrote: »

Lol are you having a laugh mate? Our whole class has no idea why only like 5% or less people do Q9. It's pretty much the shortest question on the paper, and it's an easy 50 in comparison to the rest.

Q8 could be worse though, not a whole lot to learn for it.

Actually I had a look at it a few times and it really never seemed that difficult, but it's not covered in my book and it's kinda too late to do it now.

I assumed it was harder than it looks purely because anytime my teacher mentioned it she seemed to dislike it, though I'm not sure she likes probability much in general.

Col Man

Yeah most books don't really cover it. Ha, it's true, most teachers don't really like it for some reason. But it's a good laugh.

Further geometry anyone? Groups maybe...? No, just pushing our luck now... ha.

SarcasticFairy

Can't stand Probability. My head just completely melts trying to get them out. Don't like paper two much in general though!

Davidius

I like and dislike probability.

I like it because it's not nearly as tedious as The Circle or The Line. I don't like that I can't be sure if I haven't made a complete mess of the whole thing.

I still need a bit more practice at it as I've been neglecting it in place of Statistics and Vectors.

Still, Q8 is a sure winner for its simplicity.*

*Watch out for the Maths P2 Aftermath thread where I'll announce that I made a bollox of Q8

Col Man

If you're looking for simplicity, Q9 is the place to be. No joke, some part Cs sometimes basically require us to take a given number, subtract another given number, divide by another number and then either say "Oh now this number is bigger than 1.96, question done" or else look up that final number on page 36 of the maths tables book and write down the result. Good times.

PurpleFistMixer

Hated probability. Statistics, alright, but I prefer my maths questions to be written in MATHS, not English. None of this nonsense about dice, give me some integrals, damnit.

OxfordComma

I think it's just far too risky. It's almost impossible to get attempt marks for probability. The part c's are really nasty in my opinion.

I find it interesting and all that, but I'm just not willing to take the risk of doing it. I like the statistics questions tho which is a shame.

In any case, I don't really need it for paper two. I've already got:

Trigonometry (The two easiest questions on either paper, in my opinion!)
The Circle (I really like this question and it's fairly predictable)
Vectors (Can be tricky, but generally ok)
The Line (This question varies wildly from year to year. It's either really easy or really tough. I'll stick with it and hope for the best!)

Des23

Yeah I love a bit of probability alright, the statistics questions are lovely aswell because they ask you to do the same thing every year.... Also in probability you get to draw little diagrams and colour stuff in, if you are so inclined, which easily makes it the most fun question.
Is anyone else not doing the cirlce? It just seems like a big mess of simultaneous equations... never appealed to me.

Col Man

Probability is good alright. I'm counting on it for two of my questions (well, that and statistics).

I don't like how the answers seem so arbitrary sometimes; it's not nice not knowing when you've gotten a question right or wrong.

Col Man wrote: »

Further geometry anyone? Groups maybe...? No, just pushing our luck now... ha.

I'm not doing further geometry, but I'm doing groups alright. I followed MathsManiac's further geometry webpage earlier in the year, but it's all gone from my head now...

Groups is lovely if you're interested in pure maths or abstract algebra. I've also got the further calculus and series one covered. I'll decide between the two on the day (whichever looks easier, really).

Des23 wrote: »

Is anyone else not doing the cirlce? It just seems like a big mess of simultaneous equations... never appealed to me.

I absolutely hate both the line and the circle. They're just too messy.

MathsManiac

-JammyDodger- wrote: »

I'm not doing further geometry, but I'm doing groups alright. I followed MathsManiac's further geometry webpage earlier in the year, but it's all gone from my head now...

Yay! Somebody read it!

xOxSinéadxOx

not really sure what I'm going to do on paper 2. I do quite like probabilty but I'm never sure if I've done it right or not and as somebody said it's hard to get attempt marks. the one question I definitely won't be doing is the circle. I ****ing hate it. Especially them puzzles in g, f, and c. big massive equations that take aaaaaaaages to do. the circle just takes to long, for me anyay. I wouldn't be able to get it done in 20mins

MathsManiac

xOxSinéadxOx wrote: »

... the one question I definitely won't be doing is the circle. I ****ing hate it. Especially them puzzles in g, f, and c. big massive equations that take aaaaaaaages to do. the circle just takes to long, for me anyay. I wouldn't be able to get it done in 20mins

I would rarely use g, f and c to solve problems in co-ord geom of the circle. If you have a reasonably good intuition about geometry, then I would recommend:
- draw a half-decent diagram showing the information you're given
- try to figure out how you can find the centre and the radius of the required circle(s) from the information given
- write the equation(s), using (x-h)^2 + (y-k)^2 = r^2.

Alexl

MathsManiac wrote: »

I would rarely use g, f and c to solve problems in co-ord geom of the circle.

I agree completely, geometry is the way to go! Some cirlce pt. (c)'s can be done in 2-3 mins
2007 literally took 1 minute. I suppose applied maths helps. But if you can identify 3,4,5 triangles you save so much time.

xOxSinéadxOx

MathsManiac wrote: »

I would rarely use g, f and c to solve problems in co-ord geom of the circle. If you have a reasonably good intuition about geometry, then I would recommend:
- draw a half-decent diagram showing the information you're given
- try to figure out how you can find the centre and the radius of the required circle(s) from the information given
- write the equation(s), using (x-h)^2 + (y-k)^2 = r^2.

never thought about it like that!

.:FuZion:.

MathsManiac wrote: »

I would rarely use g, f and c to solve problems in co-ord geom of the circle. If you have a reasonably good intuition about geometry, then I would recommend:
- draw a half-decent diagram showing the information you're given
- try to figure out how you can find the centre and the radius of the required circle(s) from the information given
- write the equation(s), using (x-h)^2 + (y-k)^2 = r^2.

Yeah thats exactly what I do. Works a charm.

sock puppet

I'll be doing it. Yesterday I revised probability, statistics and Q8. Three ridiculously short chapters and half the paper covered.

ya-ba-da-ba-doo

When we did probability in class i tried it, didnt like it, never looked at it again! Im happy with my questions lets just hope their nice tomorrow!

LivingDeadGirl

You're all saying Q8 is easy, it's my worst question on the paper, even worse than trig!

Fringe

MathsManiac wrote: »

Yay! Somebody read it!

I read it too! It's pretty good but I wasn't motivated enough to learn another topic. I did pick up the matrix way of writing transformations though which I find really helpful.

Rob!

Ya i love probability! but for those of you saying its a risk, it shouldn't be if you have prepared for others questions.

it takes about 15 minutes to do both prob questions so you have plenty of time to tackle everything else, although for me personally i'd be avoiding vectors cuz they just annoy me!

So i say if your half thinking about doing them, why not give them a shot? If you even partially understand them you should give them a quick look over before tomorrow. Paper 2 is far easier to revise for than paper 1.

Now lets just hope for a nice paper tomorrow!;)

(i always get worried when i see a straight forward paper 1)

xOxSinéadxOx

yeah me too, I'm worried cos paper 1 was fairly easy. and paper 2 is my worst paper so I hope it's not hard

Acid_Violet

It's a lovely straightforward logical question, only problem is it's easy to make one little tiny slip which makes everything go wrong for you.

Rob!

xOxSinéadxOx wrote: »

yeah me too, I'm worried cos paper 1 was fairly easy. and paper 2 is my worst paper so I hope it's not hard

I'm glad somebody is in the same boat as me!

I wonder if it will be different from previous years? because paper 1 was a bit all over the place on friday!

xOxSinéadxOx

I know this isn't probability but for the option section is there only 4 things they ask you on it?
maclaurins series
max/min thing
ratio test
integration by parts

is that it?

Amirani

xOxSinéadxOx wrote: »

I know this isn't probability but for the option section is there only 4 things they ask you on it?
maclaurins series
max/min thing
ratio test
integration by parts

is that it?

Yes. Couldn't be easier.

timmywex

Hate it!!

I hate the fact its all englishy, not mathsy, and you never know if your right or not!

Ill be trying the first 5 questions, but if theres anything tricky in them i may have to look at prob, i find stats and difference equations deadly though, so probability is just a pain!

xOxSinéadxOx

I have to learn all that cos I never could do it
going over vectors now and they're actually kind of hard! I nearly mind leave them out, I don't really get them. I remember them being easy though

Back Prince

i love the way it counts for 25 per cent of my whole grade and after **** paper 1 i could do with a few easy per cent

Claypigeon

Back Prince wrote: »

i love the way it counts for 25 per cent of my whole grade and after **** paper 1 i could do with a few easy per cent

What counts as 25%?

awhir

Back Prince wrote: »

i love the way it counts for 25 per cent of my whole grade and after **** paper 1 i could do with a few easy per cent

16.6%

platypus

You get attempt marks in probability if either top or bottom line is correct. This is important because its usually easy to get bottom line correct.

For example box with 10 counters, 5 red, 3 green 2 blue. If you are asked for P(3 red), the anwer would be (5C3)/(10C3) or 5/10*4/9*3/8. If your bottom line is 10C3 or 10*9*8 you get attempt mark at least. (the bottom line would be the same for any problem taking 3 items at random from 10 without replacement)

GL to all with P2:)

Back Prince

awhir wrote: »

16.6%

fuher probability for the world 25 per cent