Normal Template Exam 3 - Form A Page 1 of 2 1. А random sample of 500 American Citizens (who are at least 5 years old) contains 96 people who speak a language other than English at home. Construct a...

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Normal Template Exam 3 - Form A Page 1 of 2 1. А random sample of 500 American Citizens (who are at least 5 years old) contains 96 people who speak a language other than English at home. Construct a 90% confidence interval to estimate the true proportion of United States citizens who speak a language other than English at home. 2. The proper operation of typical home-appliances requires voltage levels that do not vary very much. Listed below are 10 voltage-levels recorded in а home on 10 different days. 123.3 123.5 123.7 123.4 123.6 123.5 123.5 123.4 123.6 123.8 Find the 95% confidence interval of the variance of the voltage-levels. 3. А random sample is chosen from a normal population with mean  = 183.2 and standard deviation  = 17.32. Find the minimum sample size which yields a maximum error of 7 at а 99% confidence level. 4. The US Bureau of Labour Statistics collects information on the ages of people in the civilian labour force and publishes the results in employment and earnings. A sample of 50 people in the civilian forces are randomly selected. Find the 95% confidence interval of the mean age of the  of all people in the civilian force.  = 12.1 years. The sample mean x = 36.4 5. A mathematician named Gosset used the following data set which gives additional sleep (in hours) obtained by a sample of 10 patients using a certain sleeping medicine. The data is 1.9 0.8 1.1 0.1 -0.1 4.4 5.5 1.6 4.6 3.4 Obtain a 95% confidence interval of the additional sleep that would be obtained by using the sleeping medicine. 6. An insurance company claims that the average automobile on the road today is less than 4 years old. A random sample of 15 cars had an average age of 5.4 years with a standard deviation of 1.1 years. Assume that the population is normally distributed. Test the claim at  = 0.01. 7. A wireless company claims that the average of the customers cell phone bill is less than $90.00 per month. A sample of 75 customers reported that their average monthly bill is $84.25 with a standard deviation of $16.03. Test the claim at  = 0.01. Exam 3 - Form A Page 2 of 2 8. А simple random sample of 40 recorded speeds in miles per hour is obtained from cars traveling on а section of Highway 405 in Los Angeles. The sample has а mean of 69.1 miles per hour and а standard deviation of 5.6 miles per hour. Use а 0.05 significance level to test the claim that the mean speed of all cars is greater than the posted speed limit of 65 miles per hour. 9. Define the following: A) Point estimate and confidence interval. B) Null hypothesis and alternate hypothesis. C) Type I error and Type II error. 10. It is claimed that the approval rating of the government of a certain state is less than 60%. Out of a random sample of 200 people, 115 people gave the government a positive rating. Test the claim at  = 0.05