probability problem

[Semidevil]

so flaws in metal produced by high temperatures occure at a rate of 1 per 10 square feet. what is the probability that there is 3 or more flaws in a 8 x 5 feet.

ok, so I know we need to use poisson disstribution on this, e^-np * np^k/k!.

howver, I dont know my np.

so 1 per 10 square feet means 1 per 10 x 10 feet....maybe we can say this is the same as .1 per 1 x 1 feet.

so how do I put this in terms of 8 x 5 feet?

 

[Heisenberg]

Umm...1 per 10x10 would be one per 100 square feet.

 

[meltdown75]

is this the *official* probability problem post?

 

[Semidevil]

Originally posted by: meltdown75
is this the *official* probability problem post?

it better be....we should make this a stickey....

 

[SchrodingersDog]

100%

 

[Semidevil]

Originally posted by: Heisenberg
Umm...1 per 10x10 would be one per 100 square feet.

oh....shooot.

anyways, can someone help me put this in terms of 8 x 5 feet?

 

[upsciLLion]

Are you using the Miller & Miller text? It sounds like a problem I had just a couple weeks ago. I'll take a look when I get home.

 

[Toastedlightly]

so, ghetto doing it, the probability seems to be 1/10 sq ft. 8x5 = 40..

 

[Semidevil]

Originally posted by: upsciLLion
Are you using the Miller & Miller text? It sounds like a problem I had just a couple weeks ago. I'll take a look when I get home.

no...it's everyones favorite...Larson and Marx

 

[SchrodingersDog]

It's 100%, you don't need to know how to arrive at answers, it's the destination that matters.

 

[olds]

50/50

 

[otispunkmeyer]

Originally posted by: Semidevil
so flaws in metal produced by high temperatures occure at a rate of 1 per 10 square feet. what is the probability that there is 3 or more flaws in a 8 x 5 feet.

ok, so I know we need to use poisson disstribution on this, e^-np * np^k/k!.

howver, I dont know my np.

so 1 per 10 square feet means 1 per 10 x 10 feet....maybe we can say this is the same as .1 per 1 x 1 feet.

so how do I put this in terms of 8 x 5 feet?

this is a poisson ratio question isnt it? i forgot how to do them!, but i could beast any probablity question only a few months ago! its amazing how quickly u forget!

Po(lambda) where Lambda = np

if u get 1 in 100 8x5 is 40 so wont it be 0.4 per 8x5?


so Po(0.4) and then crack on with what ever the formula is again is is ?^r e^-? over something (forgot if its n! or just r or r!, i have no notes with me)

please note forum doesnt like the lambda sign so those ? u see are meant to be lambda!

edit: ah found it X - Po(?) = e^-? x ?^r / r!

ok so np or ?=0.4

and you want 3 or more flaws so that means you include three which means u do this

1 - P(X less than or equal to 2)

1 - [(e^-0.4 x 0.4^0 / 0!) + (e^-0.4 x 0.4^1/1!) + (e^-0.4 x 0.4^2/2!)]

that should be it

again i could be wrong

 

[upsciLLion]

Lamda increases or decreases proportionally to the amount of sheet metal. So you have lamda = (1)(8*5/10) = 4. Otherwise otispunkmeyer's example is correct.

 

[otispunkmeyer]

Originally posted by: upsciLLion
Lamda increases or decreases proportionally to the amount of sheet metal. So you have lamda = (1)(8*5/10) = 4. Otherwise otispunkmeyer's example is correct.

yeah u mention 10sq ft, im abit confused by this, i would take that as 10 and 8x5 as 40, so lambda = 4 and not 0.4

either way the method is correct

 

[puffff]

Originally posted by: otispunkmeyer

Originally posted by: Semidevil
so flaws in metal produced by high temperatures occure at a rate of 1 per 10 square feet. what is the probability that there is 3 or more flaws in a 8 x 5 feet.

ok, so I know we need to use poisson disstribution on this, e^-np * np^k/k!.

howver, I dont know my np.

so 1 per 10 square feet means 1 per 10 x 10 feet....maybe we can say this is the same as .1 per 1 x 1 feet.

so how do I put this in terms of 8 x 5 feet?

this is a poisson ratio question isnt it? i forgot how to do them!, but i could beast any probablity question only a few months ago! its amazing how quickly u forget!

Po(lambda) where Lambda = np

if u get 1 in 100 8x5 is 40 so wont it be 0.4 per 8x5?


so Po(0.4) and then crack on with what ever the formula is again is is ?^r e^-? over something (forgot if its n! or just r or r!, i have no notes with me)

please note forum doesnt like the lambda sign so those ? u see are meant to be lambda!

edit: ah found it X - Po(?) = e^-? x ?^r / r!

ok so np or ?=0.4

and you want 3 or more flaws so that means you include three which means u do this

1 - P(X less than or equal to 2)

1 - [(e^-0.4 x 0.4^0 / 0!) + (e^-0.4 x 0.4^1/1!) + (e^-0.4 x 0.4^2/2!)]

that should be it

again i could be wrong

?

 

[otispunkmeyer]

Originally posted by: puffff

Originally posted by: otispunkmeyer

Originally posted by: Semidevil
so flaws in metal produced by high temperatures occure at a rate of 1 per 10 square feet. what is the probability that there is 3 or more flaws in a 8 x 5 feet.

ok, so I know we need to use poisson disstribution on this, e^-np * np^k/k!.

howver, I dont know my np.

so 1 per 10 square feet means 1 per 10 x 10 feet....maybe we can say this is the same as .1 per 1 x 1 feet.

so how do I put this in terms of 8 x 5 feet?

this is a poisson ratio question isnt it? i forgot how to do them!, but i could beast any probablity question only a few months ago! its amazing how quickly u forget!

Po(lambda) where Lambda = np

if u get 1 in 100 8x5 is 40 so wont it be 0.4 per 8x5?


so Po(0.4) and then crack on with what ever the formula is again is is ?^r e^-? over something (forgot if its n! or just r or r!, i have no notes with me)

please note forum doesnt like the lambda sign so those ? u see are meant to be lambda!

edit: ah found it X - Po(?) = e^-? x ?^r / r!

ok so np or ?=0.4

and you want 3 or more flaws so that means you include three which means u do this

1 - P(X less than or equal to 2)

1 - [(e^-0.4 x 0.4^0 / 0!) + (e^-0.4 x 0.4^1/1!) + (e^-0.4 x 0.4^2/2!)]

that should be it

again i could be wrong

?

heh lol, everytime i put it in it replaced it with ?, you have skills

 

[SchrodingersDog]

Lambda Lambda Lambda and Omega Mu

 

[His Lord Uberdude]

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