« previous next »

Author Question: In using the standard normal distribution to construct a confidence interval for the population ... (Read 86 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 immune system needs 9.5 hours of sleep in total darkness to recharge completely.

Did you know?

Blood is approximately twice as thick as water because of the cells and other components found in it.

Did you know?

Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.

Did you know?

Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.

Did you know?

Drug abusers experience the following scenario: The pleasure given by their drug (or drugs) of choice is so strong that it is difficult to eradicate even after years of staying away from the substances involved. Certain triggers may cause a drug abuser to relapse. Research shows that long-term drug abuse results in significant changes in brain function that persist long after an individual stops using drugs. It is most important to realize that the same is true of not just illegal substances but alcohol and tobacco as well.

Interaction web of factors that might influence locust population size. Interaction web of factors that might influence locust population size.
Exponential population growth. Exponential population growth.
Normal and sickle-cell hemoglobin. (a) Subtle differences between the conformations of hemoglobin A Normal and sickle-cell hemoglobin. (a) Subtle differences between the conformations of hemoglobin A
Distribution and Forms of Precipitation: Snow Distribution and Forms of Precipitation: Snow
How to manually find the mean, variance, and standard deviation for a set of numbers How to manually find the mean, variance, and standard deviation for a set of numbers
Population growth and growth rate, 1950 - 2100 Population growth and growth rate, 1950 - 2100
Video: Physiology of Asthma

For a complete list of videos, visit our video library