A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims “graded 200” on the sidewall of the tire. A random sample of 23 tires indicates a sample mean tread wear index of 190.7 and a sample standard deviation of 29.3.

Assuming that the population of tread wear indexes is normally distributed, construct a 90% confidence interval estimate of the population mean tread wear index for tires produced by this manufacturer under this brand name, round to two decimal places as…

A randomly selected 14 people were asked how long they slept at night. The mean time was 5.5 hours, and the standard deviation was 0.77 hour. Find the 80% confidence interval of the mean time. Assume the variable is normally distributed.

a. The tα/2 at 80% confidence level is equal to:b. Find the best point estimate of the population mean. Detailed Answer with Explanation: Calculating an 80% Confidence Interval for Average Sleep Time Sleep is a vital part of daily life,…

A randomly selected 14 people were asked how long they slept at night. The mean time was 5.5 hours, and the standard deviation was 0.77 hour. Find the 80% confidence interval of the mean time. Assume the variable is normally distributed.

a. The tα/2 at 80% confidence level is equal to:b. Find the best point estimate of the population mean. Answer: Given Data: Solution: a) The tα2 at the 80 confidence level: The significance level is calculated…

Find the critical values for a 90% confidence interval using the chi-square distribution with 13 degrees of freedom. Round the answers to three decimal places.

Finding Critical Values for a 90% Confidence Interval Using the Chi-Square Distribution In statistics, the Chi-Square distribution is frequently used to estimate population variances and test hypotheses involving categorical data. One of its important applications is in constructing confidence intervals…

The Chartered Financial Analyst (CFA) designation is fast becoming a requirement for serious investment professionals. Although it requires a successful completion of three levels of grueling exams, the designation often results in a promising career with a lucrative salary. A student of finance is curious about the average salary of a CFA charterholder. He takes a random sample of 49 recent charterholders and computes a mean salary of 100,000with a standard deviation of 42,000. Use this sample information to determine the 90% confidence interval for the average salary of a CFA charterholder.

Answer: we’ll calculate the 90% confidence interval for the average salary of CFA charterholders based on sample data. Problem Statement We are given the following sample data from a survey of recent CFA charterholders: The task is to calculate the…

The Chartered Financial Analyst (CFA) designation is fast becoming a requirement for serious investment professionals. Although it requires a successful completion of three levels of grueling exams, the designation often results in a promising career with a lucrative salary. A student of finance is curious about the average salary of a CFA charterholder. He takes a random sample of 49 recent charterholders and computes a mean salary of 100,000with a standard deviation of 42,000. Use this sample information to determine the 90% confidence interval for the average salary of a CFA charterholder.

Answer:Given Data: Solution: The significance level: α=1–0.90=0.10 The degrees of freedom: df=n–1=49–1=48 The critical value: $ t_c = t_{\frac{\alpha}{2}, df}…

A random sample of 100 credit sales in a department store showed an average sale of 130.00. From past data, it is known that the standard deviation of the population is 35.00.

(a) Determine the standard error (in dollars) of the mean.(b) With a 0.95 probability, determine the margin of error (in dollars).(c) What is the 95% confidence interval of the population mean (in dollars)? Answer : Given information : Sample mean,…