Question

An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt," February 24, 2005)...

An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt," February 24, 2005) argues that Americans are increasingly skimping on their sleep. A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. Calculate the upper bound of the 95% confidence interval for the population mean weekday sleep time of all adult residents of this Midwestern town. (Round intermediate calculations to 2 decimal places. Round the z-value and final answer to 2 decimal places.)

Homework Answers

Answer #1

Solution :

Given that,

Point estimate = sample mean = = 6.4

Population standard deviation = = 1.8

Sample size = n = 80

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

Margin of error = E = Z/2* ( /n)

= 1.96 * ( 1.8/ 80 )

= 0.39

At 95% confidence interval estimate of the population mean is,

- E < < + E

6.4 - 0.39 < < 6.4 + 0.39

6.01 < < 6.79

(6.01 , 6.79)

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
Similar Questions
An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt," February 24, 2005)...
An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt," February 24, 2005) argues that Americans are increasingly skimping on their sleep. A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. Calculate the upper bound of...
An article in the National Geographic News argues that Americans are increasing skipping on their sleep....
An article in the National Geographic News argues that Americans are increasing skipping on their sleep. A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. a. What is the margin of error for a 95% confidence interval for the...
An article in the National Geographic News (February 24, 2005) reports that Americans are increasingly skimping...
An article in the National Geographic News (February 24, 2005) reports that Americans are increasingly skimping on their sleep. A researcher wants to determine if Americans are sleeping less than the recommended 7 hours of sleep on weekdays. He takes a random sample of 150 Americans and computes the average sleep time of 6.7 hours on weekdays. Assume that the population is normally distributed with a known standard deviation of 2.1 hours. Use Table 1.
1. For a company whose total number of employees is 100, we collect data from 7...
1. For a company whose total number of employees is 100, we collect data from 7 employees ,5.2, 4.1, 10, 6.8, 3.8, 8.0, and 8.3. Using these data, write down the upper bound of the 99% CI for population mean. Assume that these data are from a normal distribution. Please provide answer with 2 decimal points. 2. From a sample of size 250, number of females is 173. What is the point estimate of population proportion? Provide an answer with...
An article in the National Geographic News (February 24, 2005) reports that Americans are increasingly skimping...
An article in the National Geographic News (February 24, 2005) reports that Americans are increasingly skimping on their sleep. A researcher wants to determine if Americans are sleeping less than the recommended 7 hours of sleep on weekdays. He takes a random sample of 150 Americans and computes the average sleep time of 6.7 hours on weekdays. Assume that the population is normally distributed with a known standard deviation of 2.1 hours. Use Table 1. a. Select the relevant null...