can someone help me solve this math problem plz... - GoFuckYourself.com

xxweekxx · 04-19-2005, 05:45 PM

An oil company purchased an option of land in Alaska. Preliminary geologic studies assigned the following prior probabilities.
P(high qualith oil) = 0.60
P(medium quality oil) = 0.20
P(no oil) = 0.20

a. What is the probability of finding oil?
b. After 200 feet of drilling on the first well, a soil test is taken. The probabilities of finding the particular type of soil identified by the test follow:
P ( soil | high quality oil) = .20
P(soil | medium-quality ) = 0.80
P(soil | no oil) = 0.20
How should the firm interpret the soil test? What are the revised probabilities, and what is the new probability of finding oil?

xxweekxx · 04-19-2005, 05:52 PM

nobodyu?

Robertf · 04-19-2005, 05:54 PM

i think the anwser is invasion.

woj · 04-19-2005, 05:55 PM

a. 80% ....

DateDoc · 04-19-2005, 05:56 PM

you dont have to drill for new oil sources when you can just take it. We have the 1st state in the Middle East States (Iraq) and soon we will be adding Iraq.

DateDoc · 04-19-2005, 05:59 PM

Quote:

Originally Posted by woj

a. 80% ....

How do you figure that?
3 parcels of land, 60%, 20% and 20% making the overall probability of finding oil 33.33% (60+20+20/3=33.33) or you could be philosophical about it and say that since there is 60% oil in finding oil in the 1st parcel then the overall chances of finding oil are still 60%.

xxweekxx · 04-19-2005, 06:00 PM

I know A is .80,

Now what is B

woj · 04-19-2005, 06:05 PM

Quote:

Originally Posted by BusterPorn

How do you figure that?
3 parcels of land, 60%, 20% and 20% making the overall probability of finding oil 33.33% (60+20+20/3=33.33) or you could be philosophical about it and say that since there is 60% oil in finding oil in the 1st parcel then the overall chances of finding oil are still 60%.

Probabily of finding no oil is 20%, so P(finding oil) = 1-P(not finding oil) so 80%

for B, use P(A|B)=P(AB)/P(B) or maybe Bayes' Theorem... don't feel like thinking...

xxweekxx · 04-19-2005, 06:09 PM

come on think man

woj · 04-19-2005, 06:09 PM

do your own homework.. lol

wjxxx · 04-19-2005, 06:09 PM

B) error - probability can`t be >1

xxweekxx · 04-19-2005, 06:10 PM

woj its me man, do it for me

woj · 04-19-2005, 06:16 PM

Quote:

Originally Posted by wjxxx

B) error - probability can`t be >1

Actually, those probabilities could work, if for example it was:
P(soil | high quality oil) = 1
P(soil | medium-quality) = 1
P(soil | no oil) = 1

It would just mean that same soil is everywhere..

xxweekxx · 04-19-2005, 06:37 PM

woj man???

Kimmykim · 04-19-2005, 06:39 PM

Quote:

Originally Posted by xxweekxx

An oil company purchased an option of land in Alaska. Preliminary geologic studies assigned the following prior probabilities.
P(high qualith oil) = 0.60
P(medium quality oil) = 0.20
P(no oil) = 0.20

a. What is the probability of finding oil?
b. After 200 feet of drilling on the first well, a soil test is taken. The probabilities of finding the particular type of soil identified by the test follow:
P ( soil | high quality oil) = .20
P(soil | medium-quality ) = 0.80
P(soil | no oil) = 0.20
How should the firm interpret the soil test? What are the revised probabilities, and what is the new probability of finding oil?

The probability of not finding oil is .20
The probability of finding high quality oil is .10
The probability of finding medium quality oil is .70

Just a guess, I hate math.

The Heron · 04-19-2005, 06:40 PM

Wow are you in my management science class haha? Got the same problem I think.

2HousePlague · 04-19-2005, 07:03 PM

The wording of the second question is fucked-up:

Quote:

Originally Posted by xxweekxx

b. After 200 feet of drilling on the first well, a soil test is taken. The probabilities of finding the particular type of soil identified by the test follow:
P ( soil | high quality oil) = .20
P(soil | medium-quality ) = 0.80
P(soil | no oil) = 0.20
How should the firm interpret the soil test? What are the revised probabilities, and what is the new probability of finding oil?

"The probabilities of finding the particular type of soil identified by the test follow:" -- not clear.

I'm going to assume, then, that the new set of probabilities are simply a latter-phase adjustment of the orginal set, and NOT intended to introduce any conditional probability (based on the accuracy of the test) as a function of the first.

If that's the case, then all we have is simply a RESTATEMENT of the probability set with weighted likelihood nested inside an A vs. B (binary) outcome.

The 2 possible binary outcomes are OIL=yes, and OIL=no. Since we are told that the probability of OIL=no is 20%, we must apply the remaining probabilities ONLY to the remainin OIL=yes binary contingency.

The solution is simply that the remaining 80% probability that there will be ANY oil (100% - 20% OIL=no) is itself subject to a SECONDARY probability, to be applied only in the case that ANY oil is found.

Hence, 80% probability of medium OIL + 20% probability of quality OIL = 100%, in the case ANY OIL is found.

New probability set:

MEDIUM = 64% (80% * 80%)
HIGH = 16% (20% * 20%)
NO OIL = 20%

j-

2HousePlague · 04-19-2005, 07:09 PM

Quote:

Originally Posted by xxweekxx

How should the firm interpret the soil test?

Oh, I forgot this part.

Answer: How the fuck should I know what the FIRM should do. Maybe they're just laundering money or something. And is the elem. stats student reading this book supposed to know what to make of soil sample readings taken from ONE well at 200 feet. This is a shitty textbook -- IMO.

j-

2HousePlague · 04-19-2005, 07:26 PM

Oops, typo:

Quote:

Originally Posted by 2HousePlague

HIGH = 16% (20% * 80%)

j-

RyanL · 04-19-2005, 07:32 PM

e=mc squared

BlueDesignStudios · 04-19-2005, 07:51 PM

you have to use bayesian probabilities, I'm too lazy to turn my brain on for this though

04-19-2005, 05:45 PM	#1
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	can someone help me solve this math problem plz... An oil company purchased an option of land in Alaska. Preliminary geologic studies assigned the following prior probabilities. P(high qualith oil) = 0.60 P(medium quality oil) = 0.20 P(no oil) = 0.20 a. What is the probability of finding oil? b. After 200 feet of drilling on the first well, a soil test is taken. The probabilities of finding the particular type of soil identified by the test follow: P ( soil \| high quality oil) = .20 P(soil \| medium-quality ) = 0.80 P(soil \| no oil) = 0.20 How should the firm interpret the soil test? What are the revised probabilities, and what is the new probability of finding oil? __________________ _________________ I am the best

04-19-2005, 05:52 PM	#2
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	nobodyu? __________________ _________________ I am the best

04-19-2005, 05:54 PM	#3
Robertf Confirmed User Join Date: Feb 2004 Posts: 392	i think the anwser is invasion. __________________ ....

04-19-2005, 05:55 PM	#4
woj <&(©¿©)&> Industry Role: Join Date: Jul 2002 Location: Chicago Posts: 47,882	a. 80% .... __________________ Custom Software Development, email: woj#at#wojfun#.#com to discuss details or skype: wojl2000 or gchat: wojfun or telegram: wojl2000 Affiliate program tools: Hosted Galleries Manager Banner Manager Video Manager Wordpress Affiliate Plugin Pic/Movie of the Day Fansign Generator Zip Manager

04-19-2005, 05:56 PM	#5
DateDoc Outside looking in. Industry Role: Join Date: Feb 2005 Location: To Hell You Ride Posts: 14,243	you dont have to drill for new oil sources when you can just take it. We have the 1st state in the Middle East States (Iraq) and soon we will be adding Iraq. __________________

04-19-2005, 06:00 PM	#7
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	I know A is .80, Now what is B __________________ _________________ I am the best

04-19-2005, 06:09 PM	#9
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	come on think man __________________ _________________ I am the best

04-19-2005, 06:09 PM	#10
woj <&(©¿©)&> Industry Role: Join Date: Jul 2002 Location: Chicago Posts: 47,882	do your own homework.. lol __________________ Custom Software Development, email: woj#at#wojfun#.#com to discuss details or skype: wojl2000 or gchat: wojfun or telegram: wojl2000 Affiliate program tools: Hosted Galleries Manager Banner Manager Video Manager Wordpress Affiliate Plugin Pic/Movie of the Day Fansign Generator Zip Manager

04-19-2005, 06:09 PM	#11
wjxxx So Fucking Banned Join Date: Feb 2005 Posts: 4,448	B) error - probability can`t be >1

04-19-2005, 06:10 PM	#12
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	woj its me man, do it for me __________________ _________________ I am the best

04-19-2005, 06:37 PM	#14
xxweekxx Confirmed User Join Date: Oct 2002 Posts: 6,780	woj man??? __________________ _________________ I am the best

04-19-2005, 06:40 PM	#16
The Heron Confirmed User Industry Role: Join Date: Apr 2001 Location: Michigan Posts: 4,488	Wow are you in my management science class haha? Got the same problem I think.

04-19-2005, 07:32 PM	#20
RyanL Confirmed User Join Date: Feb 2003 Location: Tampa, FL Posts: 1,145	e=mc squared __________________ ICQ: #126013016 :: Amateur Index

04-19-2005, 07:51 PM	#21
BlueDesignStudios Confirmed User Industry Role: Join Date: Feb 2003 Location: Australia Posts: 9,492	you have to use bayesian probabilities, I'm too lazy to turn my brain on for this though __________________ Blue Design Studios - Adult Design Specialists! Email me for a free quote: [email protected]