Please i need your help, bad!! - Math problem, could raise g

[DementedChild]

here it is: Togother Michelle, Burnie and kurt can do a job in 1 hour and 20 minutes. To do the job alone, MIchelle needs twice the time that Burnie needs and two hours more than kurt. How long would it take each to complete the job working alone?

*please somebody help!!!! It could raise my grade from a D to a B please please please please please help!!!!!!

[SarahDoubleyou]

Jennifer smells like poo, and by Jennifer i mean DementedChild, its funny cuz you really are demented, in a good way though. That problem i have solved, well at least i think i do, meet me in the aud!!!!k"

[Zombie]

Michelle=176 minutes
Burnie= 88 minutes
Kurt=56 minutes

[SarahDoubleyou]

Thank you so much!!!!!!!!! how ever did you get that answer jeez, my grade is going up up up!!!thank you, thank you, thankyou

[Pete]

that question is evil and not practical. I hope that i never see it again

[Zombie]

i'm terribly sorry, my answers are all wrong :(

somewhere in my equations I used a plus instead of a minus and it just fucked everything up... :( sorry I'll post another answer soon...

errr , how old are you by the way?

[Felicia]

bah, math. I took pre-calculus in grade 11 and 12, my grade 11 final mark was like 91% and grade 12 was in the low 80% or high 70's........ I hated the grade 12 class.......... I'll save your question and think about it when I'm not busy, maybe I'll get the answer :-P

[SarahDoubleyou]

Demented Child is 16 and dyslexic stuck in a genius's world, they put her in highly intelligent people classes and she's dyslexic, ahhh probresita. But she's really smart *wink wink*

[kylie]

o=time taken if all help
m=michelle jobtime
b=bernie jobtime
k=kurt jobtime
m=2(k+120)
b=k+120 or b-k=120
k=80-(m+B) or k-80=-m-b or -k=120-b

So by finding out M or K, you can find the rest. But i dont see any way of doing this. Most probably it is to do with the initial equation given, of o=80.



(Edited by feoric at 1:13 pm on June 17, 2003)

[Frogg]

Assuming the 3 people work linearly, we can translate the work and time in a 2dimensional plane, that is, generally:
f(x) = ax + b

in which:
- x is time
- y = f(x) = work; work is considered complete when = 1

now:
- they all start at 0 mins with 0 work done so b = 0;
- a is 1/T(person), where T(person) is an array containing the total amount of time each person takes to complete the work alone

this means:
- T(Michelle) = 2 * T(bernie) = T(kurt) + 120;
- T(Bernie) = T(kurt) / 2 + 60;

also:
- T(Michelle + Bernie + Kurt) = 80
(note that T(michelle + bernie + kurt) is not the same as T(michelle) + T(bernie) + T(kurt))

therefore, by translating the work and time of all 3 together in a 2dimensional plane, we get:
1 = [ ( 1/T(kurt + 120) ) + ( 1/ (60 + T(kurt)/2) ) + ( 1/T(kurt) ) ] * 80

from here we get T(kurt), which we then use to find T(michelle) and T(bernie)

---------
note:
im also assuming that together, the 3 all work for 80mins, having split up the job in 3 unequal parts
also remember that if the 3 together do it in 80mins, that means each one individually will take longer than that, hence the inversed proportionality. we can only relate the equation of all working together with the equations of each one individually in those terms, since we have no other information

now im no expert but i think this makes sense :)



(Edited by Frogg at 3:24 pm on June 17, 2003)

[Zombie]

sorry if im not making much sense, i just woke up

but the way i took it:

q= time taken if all help
x= michelle time alone
y=burnie time alone
z= kurt time alone

my mistake was probably putting x + y + z = q = 80

if you did it like that, you'd get a negative value of z, which is nothing short of wrong...

[kylie]

Yeah, i thought it would be x+y+z=80 too. Maybe its xyz=80, although the question does say 'together' which makes it seem like they should just be added.

[Zombie]

exactly, but it appears to be more complex than it really is.

because im thinking, if x is the time Michelle does the job with help of others, than X should be the time she takes to do it alone.
x and X have no relation whatsoever in my opinion.

so you have a couple of equations that can't relate to eachother:

x+y+z=80

;

X=2Y

;

X=Z+120

.

[DementedChild]

okay i some how found that one of the answers was six hours amking the others four and three, i am not sure if this is right, did n.e. body else get that?