The waiting times (in minutes) of a random sample of 21 people at a bank have a sample standard deviation of 4.5minutes. Construct a confidence interval for the population variance of and the population standard deviation o. Use a90% level of confidence. Assume the sample is from a normally distributed population.EWhat is the confidence interval for the population variance o²?B ) (Round to one decimal place as needed.)

Answered: The waiting times (in minutes) of a…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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In a randoms sample of six people, the mean driving distance to work was 19.7 miles and the standard deviation was 6.1 miles. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 90% confidence interval for the population mean u. Interpret the results.
The average height of students at a university from an SRS of 14 students gave a standard deviation of 2.5 feet. Construct a 95% confidence interval for the standard deviation of the height of students at the university. Assume normality for the data.
A random sample of 500 observations yields x̅ =400 and s=50. What is the 95% confidence interval for the population mean?
Records indicate that the mean weight of mature rainbow trout in Eagle Creek is 1.75 kg with a standard deviation of 0.33 kg. After years of marked oxygen depletion from pollutants in the creek, a biologist wants to see if the standard deviation, o, of weights has changed. The biologist measures the weights of 20 randomly chosen mature rainbow trout from the creek and finds that the sample standard deviation is 0.38 kg. Assume the current weights of mature rainbow trout in the creek follow a normal distribution. Does the biologist have sufficient evidence to conclude that the population standard deviation, o, differs from 0.33 kg? To answer, complete the parts below to perform a hypothesis test. Use the 0.10 level of significance.
Assume that the heights of women are normally distributed. A random sample of 20 women have a mean height of 62.5 inches and a standard deviation of 1.3 inches. Construct a 98% confidence interval for the population variance, .
Some college graduates employed full-time work more than 40 hours per week, and some work fewer than 40 hours per week. We suspect that the mean number of hours worked per week by college graduates, µ, is less than 40 hours and wish to do a statistical test. We select a random sample of college graduates employed full-time and find that the mean of the sample is 37 hours and that the standard deviation is 3 hours. Based on this information, answer the questions below. What are the null hypothesis (H,) and the alternative hypothesis (H ,) that should be used for the test? H:u is 7 In the context of this test, what is a Type I error? АТурe I error is 7 fact, u is 7 | the hypothesis that µ is ? when, in Suppose that we decide not to reject the null hypothesis. What sort of error might we be making? ?
The president of a large university wishes to compare the standard deviation of the ages of students presently enrolled to previous years. The distribution of ages has been approximately normal. Find the 90% confidence interval for the population standard deviation of the student ages of the University. A random sample of 20 university students has a standard deviation of 6.1 years in a mean of 23.8 years what is the confidence interval of the population standard deviation?
Scores on a standarized exam are known to follow a normal distribution with a standard deviation of 5. A researcher finds a random sample of 25 exam scores has a mean score of 72. Use this to find a 88% confidence interval for the mean exam score of all students taking the exam.
Assume that weights of adult females are normally distributed with a mean of 77 kg and a standard deviation of 22 kg. What percentage of individual adult females have weights between 71 kg and 83 kg? If samples of 100 adult females are randomly selected and the mean weight is computed for each sample, what percentage of the sample means are between 71 kg and 83 kg?

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