Question

# The water works commission needs to know the mean household usage of water by the residents...

The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day. They would like the estimate to have a maximum error of 0.14 gallons. A previous study found that for an average family the variance is 1.44 gallons and the mean is 16.7 gallons per day. If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water? Round your answer up to the next integer.

#### Homework Answers

Answer #1

Solution

variance=1.44

standard deviation =s =   =1.44=1.2

Margin of error = E = 0.14

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

sample size = n = [Z/2* / E] 2

n = ( 1.96* 1.2 /0.14 )2

n =282.24

Sample size = n =283

Know the answer?
Your Answer:

#### Post as a guest

Your Name:

What's your source?

#### Earn Coins

Coins can be redeemed for fabulous gifts.

##### Not the answer you're looking for?
Ask your own homework help question
ADVERTISEMENT
##### Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

ADVERTISEMENT