View Full Version : anyone good with statistics?

need to finish this problem,

traffic engineers are studying a long tunnel in colorado. if x represents the time for a vehicle to go through the tunnel, is it known that the x distribution has mean of 12.1 minutes and standard deviation of 3.8 minutes under ordinary traffic conditions. The data demonstrates a normal distribution. Under ordinary conditions, there are 50 vehicles in the tunnel at one time. what is the probability that the mean time for 50 vehicles in the tunnel will be from 11 to 13 minutes?

if anyone can help, thanks!

dp102288

12-02-06, 09:49 PM

I wish I knew but I will give you a :bump:

I should have took a stat class. :(

creeker

12-02-06, 11:32 PM

Did you phrase this correctly,are you asking a question or are you stating a fact,when you wrote "is it known"? (in the form of a question) or should it read "it is known", is 12.1 a known factor?. or are you asking a question.

creeker

12-02-06, 11:45 PM

I haven't been in school for many many years,but I like this sort of thing,I dont think mathmatics comes into it all,I'm featuring 50 cars going into a tunnel at the same time,the average one will take 12.1 to complete the trip,

some will be faster,some will be slower,so you have the deviation time of 3.8.

I think the chance of overall time being 11 to 13 mins. is 100 %. Please let me know when you find out.

I asked my 2 high schoolers, and they haven't gotten to this level in math/statistics yet. Sorry. Good luck.

JRau in central Iowa

axnguyen

12-03-06, 01:58 PM

If the mean is 12.1 minutes, and the SD is 3.8, AND we have a normal curve, then 68.27% of the cars will fall between 12.1 +/- 3.8 minutes = 8.3 minutes and 15.9 minutes.

To figure out between and 11 and 13 minutes is gonna require the use of z-score tables. If you still can't figure it out, PM me :)

axnguyen

12-03-06, 02:46 PM

Ok, so to find the z-scores = (Raw score - mean)/SD...

(11-12.1)/3.8 = -.289 and

(13-12.1)/3.8 = .237

Take those values against the z-score table to find the p value. Take the z-score -.289 which corresponds to a p-value of .3859 and the next z-score which corresponds to a p-value of .5948. This means that 38.6% of people would take between 0 and 11 minutes to get through, while 59.5% of people would take less than 13 minutes to go through. Conversely, 40.5% of people take 13 minutes or longer to get through. Anyways, minus 38.6 from 59.5 to find how many people will get through between 11 and 13 minutes.

The answer is then 20.9% of people under the given circumstances will drive through the tunnel in a time between 11 and 13 minutes.

I notice that's not exactly what the question is asking...but I believe the answer applies.

dp102288

12-04-06, 08:15 AM

Damn I don't know what you posted...and I took Pre-calculus a year ago. :leaving:

Excellent job though (if its right! :p)

hey man thanks, that helps out

ewill3rd

12-05-06, 05:38 AM

Oh man.... that's what I was going to say... :histeric:

...not really ;)

axnguyen

12-05-06, 08:02 AM

Haha, statistics is a different beast than the other mathematics (Calculus, algebra, finite, etc). Taking another math will not really help you anything in statistics as stats has it's own set of formulas and such.

Either way, if I stole the answer from anyone - sorry! :P

dp102288

12-05-06, 08:50 AM

^^ Don't worry, you didn't. We spend all our time in the Lounge so we wouldn't know anyways! :D

axnguyen

12-05-06, 08:56 AM

Lounge wh0res!

ewill3rd

12-05-06, 09:39 AM

I mentioned this before, my wife has a Masters degree in Statistics, she would have loved that one I am sure.

She's pretty busy these days with her job though.

If you hadn't gotten an answer I would have asked her for you.

I recognize some of those words, but I stopped with honors Math analysis and Trigonometry in high school.

She went on to do stuff that I can't even read.

Our new favorite show on TV is numb3rs, anybody watch it?

My wife totally loves that show!

axnguyen

12-05-06, 06:35 PM

That's cool that your wife has a Masters in Stats. I took a few stats courses in my undergrad, and had to take a few as well for my Masters in Applied Health Research.

When Numbers first began I LOVED it - after watching a good bunch of them, they started to get old and repetitive...I haven't watched any of this season yet though so maybe it's better than last?

ewill3rd

12-05-06, 07:59 PM

It's getting too "dramatic". I hate it when shows start to try to make political statements and concentrate on the "victims". It's still pretty good but they are spending a little too much time on character develpment and not enough on math! LOL

She actually has her PhD in Environmental Engineering, her undergrad is Civil and she has one more Masters in Environ. Engineering. I didn't want her to get the Stat Masters, but she really wanted it because she loves math so much.

I have been buying Numb3rs on DVD, I really like it.

dp102288

12-06-06, 09:26 AM

Wow, your wife is smart!

ewill3rd

12-06-06, 11:48 AM

Oh there's more proof than just that.

How about she spent not one dime of our money, her dad's money or anything on her 11 years in college.

All Scholarship and fellowship dollars, plus a stipend for the last few years?

Nothing but a 4.0, EVER! She is a chronic overachiever.

I am very proud of her myself but sometimes she is too smart for her own good.

She works for a DOD contractor now, doing things I don't even want to know about to protect us all. ;)

'nuff said.

axnguyen

12-06-06, 01:09 PM

That's awesome - lucky guy finding such an ambitious woman!

dp102288

12-06-06, 09:45 PM

Oh there's more proof than just that.

How about she spent not one dime of our money, her dad's money or anything on her 11 years in college.

All Scholarship and fellowship dollars, plus a stipend for the last few years?

Nothing but a 4.0, EVER! She is a chronic overachiever.

I am very proud of her myself but sometimes she is too smart for her own good.

She works for a DOD contractor now, doing things I don't even want to know about to protect us all. ;)

'nuff said.

Damn!!! Lucky you man. :thumbsup:

turbojimmy

12-07-06, 05:40 AM

That's cool that your wife has a Masters in Stats. I took a few stats courses in my undergrad, and had to take a few as well for my Masters in Applied Health Research.

When Numbers first began I LOVED it - after watching a good bunch of them, they started to get old and repetitive...I haven't watched any of this season yet though so maybe it's better than last?

I just can't get statistics to stick. It's one of those things that you either get or you don't. I took it as an undergrad and for two Master's degree programs. I still have a hard time with it, which is a problem because I actually need to apply it in my job once in a while. I usually just ask someone else :)

Jim

ewill3rd

12-07-06, 05:50 AM

I love my wife, but sometimes I wish I had married someone a little "less intelligent" ;)

Not often, but sometimes.

dp102288

12-07-06, 08:22 AM

^^ How could that be bad man? To me, it seems like that's always good!

ewill3rd

12-07-06, 09:08 AM

Well it's a long story, it's one of those "grass is greener" kind of things.

I really am grateful that I have such a wonderful wife.

I'd be lying if I said she didn't try my patience at times! :D

house, I am sorry that she couldn't help you with that other problem.

I left it on her desk but she was so busy she didn't even touch it.

Hope you made out okay anyway.

dp102288

12-07-06, 08:38 PM

I'd be lying if I said she didn't try my patience at times! :D

I think all women do that! :p :getaway:

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