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#1 Help Me ! » Trigonometric Functions » 2010-01-23 07:37:33

froggy21
Replies: 0

Hihi,

I'm trying to review for my math exam on Monday and am going through my old tests. Aah, I found my Trig Functions test (which I did horribly in) and just realized that I idiotically forgot to copy down the correct answers and am now in a panic on how to do two questions on the test. I can't seem to contact any of my classmate so I'm hoping one of you can help, pretty please <3

Picture of test: http://img.photobucket.com/albums/v673/Ashly_2x1/test.jpg
Hopefully its legible/visible.

The first one is determining the equation that models the horizontal displacement of the pendulum as a function of time. I mostly got that one right but lost half a mark somewhere. Uhhhm, if there's a chance any of you understand and can explain where my teacher took off half a mark, I'd appreciate it muchly.

The second question.....I'm just lost : \ Ahahaha, my attempted answer is not shown in the image because frankly, I'm just too embarrassed to show all the question marks my teacher placed on my paper for that one -headdesk- Uhm, the only thing I get to do is plug in the given coordinates into the equation but I don't understand where to go from there....

So if anyone can help, I'd be very grateful <3 Thank you for your time.

#2 Re: Help Me ! » expected value for three out of six cards dealt! » 2009-11-19 19:26:33

Aah, thank you very much for all your help!

We ended up using a (sort of semi-guessing, ahaha) formula for our project wherein we find the E(x) for the highest card in 6 dealt and multiplying that by 3. The value's a bit off but it does give a ballpark answer and our teacher said as long as she can follow the logic of what we were trying to attempt, then it's ok. Mofaye thought of the method while looking at the methods you gave us so thank you, because you all helped a lot : D

#3 Re: Help Me ! » expected value for three out of six cards dealt! » 2009-11-19 02:25:17

Aah, sorry about mofaye... she's a bit...meh. We don't actually have an answer for it, since this is part of our DM project (and before anyone says it's cheating by asking here, I already asked my teacher and she said we're allowed to ask other people for help). I think what mofaye meant was we can't present to her the answer that's achieved from a simulation (because it's not part of our curriculum) and we need to show the break down of how to get each probability....

Thank you still for all your help and sorry if we offended you : (

#4 Re: Help Me ! » expected value for three out of six cards dealt! » 2009-11-18 18:23:15

hallo~

I'm mofaye's partner on this inane project : P What we were planning to do was just show this method with a few examples on how to get the probabilities of a few sums as a start of point. I'm having trouble though with the equation for each probability

for example, to get a sum of 30...would it be

(16C3)*(48C3)/(52C6)

or is it

(16C3)*(48C3)/52x51x50x49x48x47?

I thought at first that it was the latter one but my brother said that the hyper geometric formula took the dependency into account already. Also, if for example, we're looking for the probability for a sum of 15. If one possible way to get that is 10, 3, 2, do we need to multiply the resulting probability by 3! to account for the permutations? : ( Sorry for asking so many questions and thank you so much for all the help so far.

#5 Re: Help Me ! » Expected value of 3 cards dealt » 2009-11-18 08:55:27

Oooh, I get it now. The tree diagram really helped.

Thank you very much, everyone for all the help! : )

#6 Re: Help Me ! » Expected value of 3 cards dealt » 2009-11-17 19:56:47

Hey bobbym,

Sorry, I understood your initial explanation because it coincided with mathsyperson's explanation, but I don't understand what you meant about it having no difference at all. Cause the probabilities will change won't it not? Counted, it's a very small and negligible difference. Like, if you draw a 1 for the first card, then the probability for 1 in the probability distribution of the deck for the second card will change from 1/13 to 3/52. Or did you mean that it's no difference -because- the change in probabilities is tiny enough to ignore?

Thank you though for your help : )

____________________________

(To simplyjasper,

But won't it turn out to be about 1000 end branches because each number on the 1st row would have a 10 branches to them, which also applies to each number on the 2nd row?)

#7 Re: Help Me ! » Expected value of 3 cards dealt » 2009-11-16 14:50:01

Thank guys! I wasn't sure if ignoring the conditional probability was ok but since ya'll confirmed that the difference is relatively negligible, I think it should be fine. Thank you very much!

#8 Help Me ! » Expected value of 3 cards dealt » 2009-11-16 02:38:49

froggy21
Replies: 11

If each card on a regular deck has points that corresponds to their number (like 2 of hearts is 2 points, 7 of clubs is 7 points), the Jack, Queen, King each being 10 points...what's the expected value of your opponent's hand if you deal them 3 cards? I know the empirical expected value...but I'd like to know -how- to get the theoretical expected value, please : )

Help please D: I've been stewing over this question for days now. The only way I can think of doing this is by doing a tree diagram to get each probability but that'll have like 1000 end branches -headdesk-

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