SOLUTION: As the new city planner for a developing community you need to project a budget for garbage trucks. To support your numbers you will use an estimate of the mean weight of garbage

Algebra ->  Probability-and-statistics -> SOLUTION: As the new city planner for a developing community you need to project a budget for garbage trucks. To support your numbers you will use an estimate of the mean weight of garbage       Log On


   

Question 275992: As the new city planner for a developing community you need to project a budget for garbage trucks. To support your numbers you will use an estimate of the mean weight of garbage discarded weekly by household.

a. Find the sample size necessary to estimate the mean if you want to be 90% confident that the sample mean is within 2 pounds of the true population mean. A sample of 62 households produced a standard deviation = 12.46 pounds

Try it again at a 95% and a 99% confidence and indicate the change in the sample size and why you think this is so.


b. Give an example from your workplace of a problem that requires you to determine a sample size.


Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
As the new city planner for a developing community you need to project a budget for garbage trucks. To support your numbers you will use an estimate of the mean weight of garbage discarded weekly by household.
a. Find the sample size necessary to estimate the mean if you want to be 90% confident that the sample mean is within 2 pounds of the true population mean. A sample of 62 households produced a standard deviation = 12.46 pounds
----
n = [z*s/E]^2
n = [invNorm(0.95]*(12.46/(sqrt(62))/2]^2
---
n = [1.96*24.92/sqrt(62)]^2
n = 38.48
Round up to n = 39
======================================
Try it again at a 95%
Change the z-value to invNorm(0.975)
---
and a 99% confidence
Change the z-value to invNorm(0.995)
-----
and indicate the change in the sample size and why you think this is so.
More confidence and sample size are directly related.
===========================================================
b. Give an example from your workplace of a problem that requires you to determine a sample size.
I'll leave that to you.
Cheers,
Stan H.