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April 21, 2026, 06:55:38 am
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Author Topic: Water's Urgent Math Methods Question:  (Read 7818 times)  Share 

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Water

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Re: Water's Urgent Math Methods Question:
« Reply #15 on: April 06, 2011, 04:23:12 pm »
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Quote from: xZero on April 06, 2011, 04:21:27 pm
ROFL I remember doing this question last yr :D

a) the machine is already broken at the start of day1 so we don't count the 0.1, so by the end of day1,2,3 and 4 the machine will not be fixed so P = (0.45)^4. By the end of day5 the machine should be fixed so P = (0.45)^4 x 0.55 and I got 0.0226 (hoping for a typo in your answer :/)

Lol........ What a bullshit question.... Cool Thanks, .... It said, "That Breaks down on day 0," was assuming that it'd be operating to broken on day 0, and they expect us to assume its broken from the very start. VERY DODGY QUESTION!


I was interpreting as, until day 5, before  day 5 actually occurs >; , so end of day 4 that its repaired haha.
« Last Edit: April 06, 2011, 04:25:31 pm by Water »
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About Philosophy

When I see a youth thus engaged,葉he study appears to me to be in character, and becoming a man of liberal education, and him who neglects philosophy I regard as an inferior man, who will never aspire to anything great or noble. But if I see him continuing the study in later life, and not leaving off, I should like to beat him - Callicle

xZero

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Re: Water's Urgent Math Methods Question:
« Reply #16 on: April 06, 2011, 04:26:58 pm »
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Quote from: Water on April 06, 2011, 04:23:12 pm
Quote from: xZero on April 06, 2011, 04:21:27 pm
ROFL I remember doing this question last yr :D

a) the machine is already broken at the start of day1 so we don't count the 0.1, so by the end of day1,2,3 and 4 the machine will not be fixed so P = (0.45)^4. By the end of day5 the machine should be fixed so P = (0.45)^4 x 0.55 and I got 0.0226 (hoping for a typo in your answer :/)

Lol........ What a bullshit question.... Cool Thanks, .... It said, "That Breaks down on day 0," was assuming that it'd be operating to broken on day 0, and they expect us to assume its broken from the very start. VERY DODGY QUESTION!

yup rofl, I said 'WTF' out loud in class last year when the teacher showed us why we were tricked  :o
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Water

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Re: Water's Urgent Math Methods Question:
« Reply #17 on: April 13, 2011, 01:42:12 pm »
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Consider the random variable Y with probability density function with the rule

f(y) = ke^-y          y > or equal to 0

         0                     y < 0



Find

a) the constant K.



Dunno how to do it ):!
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Re: Water's Urgent Math Methods Question:
« Reply #18 on: April 13, 2011, 01:58:16 pm »
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Area under the graph f(y) is = 1. So:







But since when , , then:



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Water

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Re: Water's Urgent Math Methods Question:
« Reply #19 on: April 13, 2011, 02:47:47 pm »
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Ohh shit, yes yes, LOL, i forgot the anti derivative of e, Damn Me, so stupid, thankyou so much :)
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Water

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Re: Water's Urgent Math Methods Question:
« Reply #20 on: April 13, 2011, 09:31:08 pm »
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A Random Variable X has a cumulative distribution function

f(x) = 0         x<0

      = 1 - e^-x^2      x > or equal to 0


b) Find Pr (X> or equal to 2)



I can't seem to find the integral of 1 - e^(~~~), tried consulting my calculator as well, is there a method for this?
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About Philosophy

When I see a youth thus engaged,葉he study appears to me to be in character, and becoming a man of liberal education, and him who neglects philosophy I regard as an inferior man, who will never aspire to anything great or noble. But if I see him continuing the study in later life, and not leaving off, I should like to beat him - Callicle

Water

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Re: Water's Urgent Math Methods Question:
« Reply #21 on: April 13, 2011, 10:20:23 pm »
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bump *
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jane1234

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Re: Water's Urgent Math Methods Question:
« Reply #22 on: April 13, 2011, 10:24:58 pm »
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Quote from: Water on April 13, 2011, 09:31:08 pm
A Random Variable X has a cumulative distribution function

f(x) = 0         x<0

      = 1 - e^-x^2      x > or equal to 0


b) Find Pr (X> or equal to 2)



I can't seem to find the integral of 1 - e^(~~~), tried consulting my calculator as well, is there a method for this?
Are you sure this is the correct equation?? Because I tried Pr(X>equal to 2) and it gave me a huge number... when probabilities should be less than one.
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Water

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Re: Water's Urgent Math Methods Question:
« Reply #23 on: April 13, 2011, 10:25:38 pm »
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Yeah, Pr X> or equal to 2)

the answer is e^-4 based from book
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About Philosophy

When I see a youth thus engaged,葉he study appears to me to be in character, and becoming a man of liberal education, and him who neglects philosophy I regard as an inferior man, who will never aspire to anything great or noble. But if I see him continuing the study in later life, and not leaving off, I should like to beat him - Callicle

xZero

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Re: Water's Urgent Math Methods Question:
« Reply #24 on: April 13, 2011, 10:25:44 pm »
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I don't think you can integrate this with methods knowledge so just solve the integral with your calc
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Water

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Re: Water's Urgent Math Methods Question:
« Reply #25 on: April 13, 2011, 10:27:02 pm »
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How am I  meant to integral this with my calc? It doesn't integrate the 1 - e^ -x^2 for me ):


« Last Edit: April 13, 2011, 10:29:29 pm by Water »
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xZero

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Re: Water's Urgent Math Methods Question:
« Reply #26 on: April 13, 2011, 10:29:33 pm »
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just to make sure, the integral is right
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Water

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Re: Water's Urgent Math Methods Question:
« Reply #27 on: April 13, 2011, 10:29:51 pm »
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And yes, that is the integral


Doesn't work .

Just gives me x- integral  ( e^-x^2 ) dx
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About Philosophy

When I see a youth thus engaged,葉he study appears to me to be in character, and becoming a man of liberal education, and him who neglects philosophy I regard as an inferior man, who will never aspire to anything great or noble. But if I see him continuing the study in later life, and not leaving off, I should like to beat him - Callicle

jane1234

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Re: Water's Urgent Math Methods Question:
« Reply #28 on: April 13, 2011, 10:31:22 pm »
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If you plot the graph of the equation there is no way the total area is equal to one. So it can't be a pdf.
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xZero

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Re: Water's Urgent Math Methods Question:
« Reply #29 on: April 13, 2011, 10:34:28 pm »
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just solve for and the Pr(x> or equal to 2) = 1 - Pr(0<x<2), but I got 1.1179 for the integral so ... :S
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