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Topic: Anybody Out Here Good At Math?
whispertoascream Joined Fri 11/17/06 Posts: 22844	Tue 09/11/07 11:14 AM
I am currently taking grade 12 collage apprenticeship math. And right now we are talking about The Normal Distribution and the Regression line of Best Fit. It is this whole bell curve thing. Does anybody no anything about this stuff? If so PLEASE I am begging you HELP! One day in this class is like one week. I have a test tomorrow and we just got this yesterday.

BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 11:15 AM
Yea...what's the specific question?

Coolhead Joined Mon 01/22/07 Posts: 2525	Tue 09/11/07 11:16 AM
Yes, but don't want to add up now! Good luck

Tlc4359 Joined Tue 08/14/07 Posts: 4	Tue 09/11/07 11:19 AM
You obviously have internet access - look it up.

whispertoascream Joined Fri 11/17/06 Posts: 22844	Tue 09/11/07 11:20 AM
One of the questions is The usable lifetimes of 10,000 AA batteries are normally distributed with a mean life time of 25 hours and a standard deviation of 2 hours. a) Determine the lifetimes that are within 1.2 and 3 standard deviations of the mean. b) What percent of the batteries have a usable lifetime in each range? i) 23 hours and 27 hours? Ii) 29 and 31 hours? iii) 19 and 27 hours?

whispertoascream Joined Fri 11/17/06 Posts: 22844	Tue 09/11/07 11:21 AM
Tic, I have looked it up, I just can not seem to get the grasp of it so I am asking for help like anybody else would.

BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 11:21 AM
You must have formulas to plug these numbers into, don't you?

whispertoascream Joined Fri 11/17/06 Posts: 22844	Tue 09/11/07 11:22 AM
We are supposed to use a bell curve.

Gypsy41 Joined Tue 05/15/07 Posts: 123359	Tue 09/11/07 11:25 AM
oh crap!!!!! Tell your teacher that you will never have to use this crap in your life and to stick it up his azzzzzzzzzzz!!!!!

one9delta Joined Tue 09/11/07 Posts: 384	Tue 09/11/07 11:28 AM
dude what the hell i just graduated college and never had a question that hard

kojack Joined Mon 12/25/06 Posts: 16382	Tue 09/11/07 11:33 AM
www ask jeeves

BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 11:34 AM
You've gotta plot these on a graph, don't you?

whispertoascream Joined Fri 11/17/06 Posts: 22844	Tue 09/11/07 11:39 AM
Yes.

BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 11:45 AM
You got email.

MsTeddyBear2u Joined Fri 04/06/07 Posts: 22031	Tue 09/11/07 11:48 AM
Wow I need to go back to school... Sorry can't help you...

BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 12:00 PM
If anyone cares to know the answer, I think this is it. If I am wrong, let me know! To answer part (a), for any normal distribution 68.2% fall within the 1 std deviation, 95.4 within 2 and 99.7 within 3. For part (b), (i) is the same as 1 std deviation. (ii) will be half of values within (3 std dev - 2 std dev), ie 2.15% and (iii) will be half of values with in 3 std devs + half of values with in 1, ie 83.95%

MsTeddyBear2u Joined Fri 04/06/07 Posts: 22031	Tue 09/11/07 12:23 PM


BayAreaGal Joined Sat 07/28/07 Posts: 6070	Tue 09/11/07 12:25 PM


bobson Joined Fri 05/18/07 Posts: 562	Tue 09/11/07 07:01 PM
WHY ARE WE DOING MATH?! when I came here, I was specifically told: NO MATH

Poly Joined Fri 08/17/07 Posts: 223	Tue 09/11/07 07:23 PM
The answers to part a are given in part b, but this is where they came from: 1 standard deviation 25-2(1)=23 25+2(1)=27 2 standard deviations 25-2(2)=21 25+2(2)=29 3 standard deviations 25-3(2)=19 25+3(2)=31 For part b, it depends on your text book and teacher, in my classes, 68% fell within 1 standard deviation, 95% fell within 2 standard deviations, and virtually all (98+%) fell within 3 standard deviations.