# Sampling Distributions help

#### franklinexpress

##### New Member
Hi, I'm teaching myself stats but have no idea on how to solve these, any help would be appreciated.

When a pizza restaurant’s delivery process is operating effectively, pizzas are delivered in an average of 45 minutes with a standard deviation of 6 minutes. Suppose each night, 9 deliveries are selected at random and their delivery times are recorded. For the sake of argument, assume that the pizza deliveries are normally distributed.

1) What is the probability that the average time for the sample mean each night is within 2 minutes of the population mean?

2) What is the probability that the average time for the sample mean each night is within 2.5 minutes of the mean?

3) What is the probability that the average time for the sample mean is within 4 minutes of the mean?

A study was conducted to estimate the cost of employee absences. Based on this research, the amount of paid-time lost over a 3 month period was found to be normally distributed with a mean of 1.5 days and a standard deviation of 2.5 days. A sample of 100 employees was taken, find

4) The probability that the sample mean is greater than 1.6 days?

5) The probability that the sample mean is within a ½ day of the population mean?

6) The probability that the sample mean is between 1.35 and 1.85 days?

7) Suppose a population is normally distributed with a mean of 5,000 and a standard devation of 1,000. A sample of size 100 is taken, what is the standard error?

#### franklinexpress

##### New Member
anyone? I really need help with this, please someone out there has got to be able to help with this

#### franklinexpress

##### New Member
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#### bugman

##### Super Moderator
This forum is F*cking useless, never logging in again.
So, you wont mind being banned for life then?
Don't come to this forum without showing any effort and expect answers straight away. This is a free service, maintained by members who are generally pretty busy.

If you want to hang around, fine. Show some effort and lose the attitude otherwise I will ban you.

#### gianmarco

##### TS Contributor
I can't believe my eyes :-O
How can people react that way?!?!?

#### spunky

##### Can't make spagetti
what i love the most aboutt his post is that the questions are so.freaking.easy yet none of us really wanted to help... lol

#### Dason

##### Ambassador to the humans
what i love the most aboutt his post is that the questions are so.freaking.easy yet none of us really wanted to help... lol
They aren't easy if you have no idea how to start. I was just put off by the horrible attitude. I would have posted my typical homework help response though (although somewhat modified) if I would have read the thread before they decided to insult the community as a whole.

#### BGM

##### TS Contributor
OP is really amazing impatient... and show his horrible attitude within 3 hours from the first post...

BTW Dason maybe you can make your standard homework help message as a button?

#### bugman

##### Super Moderator
Good idea BGM, we seem to need it pretty often.

#### Dason

##### Ambassador to the humans
OP is really amazing impatient... and show his horrible attitude within 3 hours from the first post...

BTW Dason maybe you can make your standard homework help message as a button?
It is a button for me in my browser but I don't really have the ability to add buttons to the forum. We could probably make a request to quark in the forum feedback section though.

#### hlsmith

##### Less is more. Stay pure. Stay poor.
Express indeed (verbose or expedience?)

#### Dason

##### Ambassador to the humans
OP is really amazing impatient... and show his horrible attitude within 3 hours from the first post...

BTW Dason maybe you can make your standard homework help message as a button?
If you're interested I just have the message as a button on my bookmarks bar in Chrome. You can do it in Firefox too - just add a bookmark on the bookmark bar and have this be the bookmark:
Code:
javascript:window.prompt("Copy to clipboard: Ctrl+C, Hit cancel", 'Hi! :welcome: We are glad that you posted here! This looks like a homework question though.  Our homework help policy can be found [url="http://www.talkstats.com/showthread.php/57-We-only-provide-homework-help-to-those-who-show-effort"]here[/url].  We mainly just want to see what you have tried so far and that you have put some effort into the problem.  I would also suggest checking out [url="http://www.talkstats.com/showthread.php/14960-Forum-Guidelines-Smart-posting-behavior-pays-off"]this thread[/url] for some guidelines on smart posting behavior that can help you get answers that are better much more quickly.')