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    (Original post by raceforthefishman)
    YAY


    :hubba:
    Want to try and help me and my friend with a delicious C3 question??

    *couldn't remember whether lozz does maths *
    Erm depends, I'm kinda failing at C3 atm :p:
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    (Original post by lozz2601)
    I do, but I'm not sure I'll be any more help than if I didn't!
    I'll post it, its infuriating because we just can't see it!

    Spoiler:
    Show
    An epidemic is spreading exponentially through a community, so that the total number of people who have been admitted to hospital in the first t weeks (including those who have subsequently been discharged) is modelled by the equation y=5e0.3t

    Patients remain in hospital for 2 weeks and then are discharged. Find an expression for the number of patients in hospital after t weeks (for t>= 2) and show that this number also increases exponentially....

    Its so annoying
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    seriously right, who else is sick of checking track and seeing nothing. cuz i am.
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    (Original post by raceforthefishman)
    I'll post it, its infuriating because we just can't see it!

    Spoiler:
    Show
    An epidemic is spreading exponentially through a community, so that the total number of people who have been admitted to hospital in the first t weeks (including those who have subsequently been discharged) is modelled by the equation y=5e0.3t

    Patients remain in hospital for 2 weeks and then are discharged. Find an expression for the number of patients in hospital after t weeks (for t>= 2) and show that this number also increases exponentially....

    Its so annoying
    thats a bit of a tricky one :erm:
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    (Original post by jaz_jaz)
    seriously right, who else is sick of checking track and seeing nothing. cuz i am.
    I know nothing's gonna happen with mine now forever so I've sorta given up.....

    and er that question is evil.
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    I know I can't get any more offers
    *have to be given an interview for one...and have to do my interview for the other*

    yet i still check it
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    I just check my emails!
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    I swear this question is impossible
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    (Original post by raceforthefishman)
    I swear this question is impossible
    It actually is!
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    Where's ghosh when you need him
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    :sadnod:

    also grr, trying to learn what kind of more basic *cough* cheaper *cough* microscope I can pimp out with a condensor set up for phase contrast.....and failing....
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    (Original post by raceforthefishman)
    I'll post it, its infuriating because we just can't see it!

    Spoiler:
    Show
    An epidemic is spreading exponentially through a community, so that the total number of people who have been admitted to hospital in the first t weeks (including those who have subsequently been discharged) is modelled by the equation y=5e0.3t

    Patients remain in hospital for 2 weeks and then are discharged. Find an expression for the number of patients in hospital after t weeks (for t>= 2) and show that this number also increases exponentially....

    Its so annoying
    For the first 2 weeks there are no patients leaving.

    Then from that point on, the number of patients in the hospital is defined by y=5e0.3t minus the number of patients there 2 weeks ago.

    So it'd be

    Week 1 y=5e0.3 +
    Week 2 y=5e0.6 +
    Week 3 y=5e0.9 - y=5e0.3 +
    Week 4 y=5e1.2 - y=5e0.6

    Etc etc

    So every week it's expanding exponentially.

    I don't know if I'm right but it looks like it might be

    Though I dunno if that's proof of any sort.
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    (Original post by ArchedEdge)
    For the first 2 weeks there are no patients leaving.

    Then from that point on, the number of patients in the hospital is defined by y=5e0.3t minus the number of patients there 2 weeks ago.

    So it'd be

    Week 1 y=5e0.3 +
    Week 2 y=5e0.6 +
    Week 3 y=5e0.9 - y=5e0.3 +
    Week 4 y=5e1.2 - y=5e0.6

    Etc etc

    So every week it's expanding exponentially.

    I don't know if I'm right but it looks like it might be

    Though I dunno if that's proof of any sort.
    Ye thanks, I'd worked that out
    Whats the most annoying is the book gives a formula that will work out the number of patients discharged each week

    definitely a start though, any ideas with a formula?
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    (Original post by raceforthefishman)
    Ye thanks, I'd worked that out
    Whats the most annoying is the book gives a formula that will work out the number of patients discharged each week

    definitely a start though, any ideas with a formula?
    What is the answer they give?

    And they have a formula for exactly the number of patients discharged each week? Isn't that just y=5e0.3(t-2)?
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    (Original post by ArchedEdge)
    What is the answer they give?

    And they have a formula for exactly the number of patients discharged each week? Isn't that just y=5e0.3(t-2)?
    they give it as
    2.26e0.3t

    I can understand the 0.3t as the rate of coming and going is going to be the same

    and I can understand why they constant is different -- flow of people leaving per week and all that...and its less as the original constant was cumulative of people coming and going

    but the number just seems random!
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    (Original post by raceforthefishman)
    they give it as
    2.26e0.3t

    I can understand the 0.3t as the rate of coming and going is going to be the same

    and I can understand why they constant is different -- flow of people leaving per week and all that...and its less as the original constant was cumulative of people coming and going

    but the number just seems random!
    I dunno
    Post a thread in the maths forum, at this time of the day you'll get an answer within minutes!
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    (Original post by Champagne Supernova)
    I just check my emails!
    J'arrive! Queerly enough, I was baking a cake
    (Original post by raceforthefishman)
    they give it as
    2.26e0.3t

    I can understand the 0.3t as the rate of coming and going is going to be the same

    and I can understand why they constant is different -- flow of people leaving per week and all that...and its less as the original constant was cumulative of people coming and going

    but the number just seems random!
    After t weeks, there have entered  5e^{0.3t} people, and left  5e^{0.3(t-2)} people (as it is the number of people that entered two or more weeks before).

    Hence the number of people in the hospital in week t, for t greater than or equal to 2, is the difference, which is after factorising:

     5e^{0.3t}(1 - e^{-2\times 0.3})
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    interview at liverpool, im crapping myself
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    (Original post by clad in armour)
    interview at liverpool, im crapping myself
    welll done!
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    (Original post by bob9001)
    welll done!
    thanks a lot mate, judging by your sig, you are gonna be seriously busy (unless youve had them already) if theres any congratulations its for you!
 
 
 
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