Probability Density Function Help

[Jingle Bells]

I have been attempting this homework question for a very long time, yet i still cannot figure out. I don't know what properties or what concepts of a probability density function i would need solve for C.

 

[Steven G]

You want [math]\int_{100}^{\infty} p(R) dR[/math] >.8

Just solve that for c. Also C and c are NOT the same.

Post back with your work and we can check to see if you are correct.

 

[tkhunny]

1) The variable R does not appear in the denominator. It should be easy enough to calculate an integral and thus, an accumulated probability.

 

[Jingle Bells]

You want [math]\int_{100}^{\infty} p(R) dR[/math] >.8

Just solve that for c. Also C and c are NOT the same.

Post back with your work and we can check to see if you are correct.

Hey there just a quick question how come you set up your bounds from 100 to infinity, initially when i tried this problem i did try integrating the function with respect to R, but my bounds were 100,000 to 1,000,000. Then using an integral calculator i got the following answer.

 

[Steven G]

Hey there just a quick question how come you set up your bounds from 100 to infinity, initially when i tried this problem i did try integrating the function with respect to R, but my bounds were 100,000 to 1,000,000. Then using an integral calculator i got the following answer. View attachment 20704

I just reread your original post. The upper limit should be 1,000,000

 

[Jingle Bells]

I just reread your original post. The upper limit should be 1,000,000

Thank you but do you think that the initial inequality which was >= 0.80, or should it just be 0.80, because i also re-read the wording and by the looks of it i feel that it might just be = 0.80. However though i did try the >= 0.80 inequality and i couldn't find a online calculator that could properly compute it.

 

[Steven G]

Online calculator? You are trying to do a math problem so use math.

 

[Jingle Bells]

Online calculator? You are trying to do a math problem so use math.

right but the numbers are extremely large, they are almost impossible to do by hand.

 

[Dr.Peterson]

Thank you but do you think that the initial inequality which was >= 0.80, or should it just be 0.80, because i also re-read the wording and by the looks of it i feel that it might just be = 0.80. However though i did try the >= 0.80 inequality and i couldn't find a online calculator that could properly compute it.

The words "at least" in the problem mean "[MATH]\ge[/MATH]". (So does "find the smallest".)

But the main work can be done in terms of an equality.

Now, please tell us what skills this is supposed to be giving you practice in. An online calculator could be appropriate if the goal is to know what math has to be done, not to know how to carry out details; but do you know what math has to be done? What do you want a calculator to do for you? Then you can decide whether you can do it yourself (and thereby get more practice). And you can always use a calculator to handle big numbers while you do the math yourself.

 

[Jingle Bells]

The words "at least" in the problem mean "[MATH]\ge[/MATH]". (So does "find the smallest".)

But the main work can be done in terms of an equality.

Now, please tell us what skills this is supposed to be giving you practice in. An online calculator could be appropriate if the goal is to know what math has to be done, not to know how to carry out details; but do you know what math has to be done? What do you want a calculator to do for you? Then you can decide whether you can do it yourself (and thereby get more practice). And you can always use a calculator to handle big numbers while you do the math yourself.

In terms of skills are professor says these HW questions are supposed to make us think more critically about probability concepts, he specifically told us that we are allowed to use online calculator aids, since these numbers get quite large.

 

[Dr.Peterson]

Right, the concepts are the important thing. (I think of it as learning to be a "math supervisor", who decides what has to be done, and maybe can train underlings to do it, rather than having to carry out all the details.)

So what do you want to ask a calculator to do for you? If you want to find a calculator to do it, the first step is to define the task (so you can "hire" the right employee, with the right skills).