# application of normal distribution - very lost on how to start

• Jan 29th 2009, 11:59 AM
Sweetpea
application of normal distribution - very lost on how to start
This is a question I have ... I am lost on how to do this when there is an extra number like the 50 put in. Can someone explain how to do this?

In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1050k Wh and a standard deviation of 218k Wh. If 50 different homes are randomly selected, find the probability that their mean energy consumption level for September is greater than 1075k Wh.
https://ol.baker.edu/images/spacer.gif 0.2910 0.0438 0.2090 0.4562
• Jan 29th 2009, 04:17 PM
mr fantastic
Quote:

Originally Posted by Sweetpea
This is a question I have ... I am lost on how to do this when there is an extra number like the 50 put in. Can someone explain how to do this?

In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1050k Wh and a standard deviation of 218k Wh. If 50 different homes are randomly selected, find the probability that their mean energy consumption level for September is greater than 1075k Wh.
https://ol.baker.edu/images/spacer.gif 0.2910 0.0438 0.2090 0.4562

Use the sampling distribution of the mean. Read this: Sampling Distribution of the Mean
• Jan 30th 2009, 12:09 PM
Sweetpea
still lost
uh oh I forgot to write that those last four set of numbers were the multiple choice answers. Thank you for the info on distr. of mean.

If I set up the mean there are only two numbers 1050 k Wh and then the greater than 1075 k Wh. Do I then subtract this and then divide by the standard deviation?
• Jan 30th 2009, 12:36 PM
mr fantastic
Quote:

Originally Posted by Sweetpea
uh oh I forgot to write that those last four set of numbers were the multiple choice answers. Thank you for the info on distr. of mean.

If I set up the mean there are only two numbers 1050 k Wh and then the greater than 1075 k Wh. Do I then subtract this and then divide by the standard deviation?

I had realised that the last four numbers were multiple choice options.

What I want you do is post the formulae you're using and show the details of the calculations you have done so far. That will make it easier to give you any further help that you need.