« previous next »

Author Question: In using the standard normal distribution to construct a confidence interval for the population ... (Read 48 times)

cagreen833

  • Hero Member
  • *****
  • Posts: 544
on: Jun 24, 2018
In using the standard normal distribution to construct a confidence interval for the population mean, what assumptions are necessary if the sample size n is less than 30?

Question 2

A city-paid consumer advocate wants to secure information about the mean length, , of coin-separated car wash cycles. A previous study reported the standard deviation of the length of car wash cycles to be 6 minutes. The advocate timed the wash cycle at 81 randomly selected car wash locations and the mean of the sample was 4.8 minutes. The 90 percent confidence interval estimate is 3.70 to 5.90 minutes. Interpret this interval.


emily12345

  • Sr. Member
  • ****
  • Posts: 321
Reply #1 on: Jun 24, 2018
Answer to Question 1

In this case, we need to assume that the population is normally distributed and the population standard deviation  is known.

Answer to Question 2

We have 90 confidence that the population mean is included in this interval.


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

The Centers for Disease Control and Prevention (CDC) was originally known as the Communicable Disease Center, which was formed to fight malaria. It was originally headquartered in Atlanta, Georgia, since the Southern states faced the worst threat from malaria.

Did you know?

In 2012, nearly 24 milliion Americans, aged 12 and older, had abused an illicit drug, according to the National Institute on Drug Abuse (NIDA).

Did you know?

Parkinson's disease is both chronic and progressive. This means that it persists over a long period of time and that its symptoms grow worse over time.

Did you know?

The oldest recorded age was 122. Madame Jeanne Calment was born in France in 1875 and died in 1997. She was a vegetarian and loved olive oil, port wine, and chocolate.

Did you know?

Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.

Predators and Population Cycles Predators and Population Cycles
Distribution of Rods and Cones on the Retina Distribution of Rods and Cones on the Retina
The Inverted Income Pyramid: The Proportion of Income Received by Each Fifth of the U.S. Population The Inverted Income Pyramid: The Proportion of Income Received by Each Fifth of the U.S. Population
Distribution and Forms of Precipitation: Graupel and Hail Distribution and Forms of Precipitation: Graupel and Hail
How to find the tangential and normal components of a vector How to find the tangential and normal components of a vector
World Population Growth World Population Growth
Video: Major Elements in Biological Molecules: Nucleic acids

For a complete list of videos, visit our video library