Math Is Fun Forum

NESIC

Member

Registered: 2010-09-25

Posts: 16

Probability

A person owns 2 cars, one a compact and one a standard model. About ¾ of the times he uses compact car to travel to work and gets home by 5:30 about 75% of the times. If he uses standard car he gets home by 5:30 about 60% of the times. If he gets home by 5:35, what is the probability that he used the compact car?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi NESIC;

This problem is another one similar to other you asked.
That one you had done for you.
You are not showing any work.
Homework problems are just that homework problems.
They are for you to learn from.
Your teacher thinks you can do this. Now give it a try, what does your notes say?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

Dear i need help how i solve this question, What should i find 1st and what we need to find towards solution.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

My concept regarding probability not clear i need help in this regard

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: Probability

Bayesian Theorem

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X'(y-Xβ)=0

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi;

Bayesian Theorem

Hi George:

Can you use Bayes theorem here?
Does not the question need to amended before any solution can be attempted?

Hi NESIC;

Here is an example of what I mean:

http://www.mathisfunforum.com/viewtopic … 14#p151614

Post #52, she is behind you but working much harder.

This is a conditional probability. Did you see what Candide did in the other post?
Have you copied the problem correctly? Is the 5:35 correct? Is the 5:35 incorrect?
I mean can we tell anything about the probability of getting home 5 minutes later from
the provided information. Can we tell if the man likes Jello?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

I will share my work with you, thanks for your help

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi;

I have not provided any help.

What I need is for you to answer some of the questions so that we can begin to understand the problem and do it.
At exam time are you going to carry me around in a back pack?
Do you trust my answers blindly? You have to learn how to do this.
I will help with everything I have.
Now come on, let us start here, what about the 5:35?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

by using compac car the probability that he reached home after 05:30 is .25
by using standard car the probability that he reached home after 05:30 is .40

Last edited by NESIC (2010-10-05 00:48:36)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi;

Okay!

Where does the problem come from please? What book?

As George pointed out one way to do this is by Bayes theorem. There is another way but I do not understand it.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

i don,t know about book but 50 question was given to us by teacher to improve skills

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi;

No textbook? That is weird. There must be some book because this is a textbook problem. Are you sure?

Usually today they even know the answer, in this case I believe it is .6522. At least that is what my notes say.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

Introduction to statistical theory but question not belongs to this book

Last edited by NESIC (2010-10-05 07:14:50)

NESIC

Member

Registered: 2010-09-25

Posts: 16

Re: Probability

Kindly correct me if there is any mistakes

A person owns 2 cars, one a compact and one a standard model. About ¾ of the times he uses compact car to travel to work and gets home by 5:30 about 75% of the times. If he uses standard car he gets home by 5:30 about 60% of the times. If he gets home by 5:35, what is the probability that he used the compact car?

P(C)=.75
P(C/05:35)= .25
P(S)= .60
P(S/5:35)= .40
P(05:35/C)=?

P(05:35/C)=  P(C).P(C/05:35)÷P(C).P(C/05:35)+P(S).P(S/5:35)
P(05:35/C)=.43 Ans

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability

Hi;

That title is very common, can I have the author please.

P(C) = .75
P(S) = .25
P(5:30 | C) = .75
P(5:30 | S) = .60

P(5:35 | C) = .25
P(5:30 | S) = .40

You are looking for:

P(C | 5:35)

Can you take it from here?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.