Police recorded the average speed of cars driving on a busy street by a school. For a sample of 16 speeds, it was determined that the average amount over the speed limit for the 16 speeds was 11.4 mph with a standard deviation of 6 mph. The 90% confidence interval estimate for this sample is 8.77 mph to 14.03 mph. a) What is the margin of error for this problem? b) What size sample is needed to reduce the margin of error to no more than 1 17

The Food and Drug Administration has determined that a substance called Melamine poses a health threat when it contaminates food. In fact, it poses a health threat even to dogs when it is in their food. Consequently, the FDA wants to monitor shipments of dog food imported into the country. From previous studies on dog food, the FDA knows that the population mean of Melamine in dog food is 8.0 grams in a 40 pound bag, with a population standard deviation of 1.5 grams. How likely would it be that a random sample of 36 40-pound bags of dog food would have a mean of more than of 8.4 grams of Melamine per bag? All bags have at least 8 grams 0.05 0.50 None of the bags will have less than 8 grams

The Sydney Airport Commission set a performance target of 26 minutes for the time taken for passengers to claim their luggage at domestic terminals. In order to monitor performance a study was conducted by taking a random sample of 200 passengers disembarking from Sydney airport. If the study found a p-value of 0.5 what was the sample mean time taken by passengers to claim their luggage? (Your answer should be correct to one decimal place.)

A simple random sample with n = 54 provided a sample mean of 25.5 and a sample standard deviation of 4.4. (Round your answers to one decimal place.) (a) Develop a 90% confidence interval for the population mean. to (b) Develop a 95% confidence interval for the population mean. to (c) Develop a 99% confidence interval for the population mean. to

True or False? When the population variance is unknown and the size of a random sample is 20, then the student’s t used to construct a 90% confidence interval for the population mean is 1.729, by Appendix D.

A major newspaper (that rhymes with Small Street Journal) reported an average household income for its subscribers is $119,155. Assume this estimate of the mean household income is based on a sample of 80 subscribers, and, based on past studies, the population standard deviation is known to be sigma=$30,000. Construct a 95% confidence interval for the population mean. Group of answer choices $60,356 - $177,954 $118,420 - $119,890 $112,447 - $125,863 $112,581 - $125,729

A lumber company is making boards that are 2701.02701.0 millimeters tall. If the boards are too long they must be trimmed, and if they are too short they cannot be used. A sample of 2222 boards is made, and it is found that they have a mean of 2703.92703.9 millimeters with a variance of 100.00100.00. Is there evidence at the 0.10.1 level that the boards are either too long or too short? Assume the population distribution is approximately normal. Is there sufficient evidence to support the claim that the boards are either too long or too short?

q25-  A too wide confidence interval means that Select one: a. estimation is done with high precision b. confidence interval is informative c. estimation is done with a high degree of sampling variability d. the sample size is large Clear my choice

Air Quality Index is a way to measure particle pollution in the air. An index between 0 and 50 is considered good; between 51 and 100 is moderate; more 100 is considered unhealthy for sensitive groups and others. A recent sample data of air quality index values for Pomona in Southern California provided the following data. 50, 52, 59, 56, 58 What are the sample mean, sample variance and the sample standard deviation?

The historic average and standard deviation of the percentage moisture content MC of a product is E(MC) = 78.5% and sMC = 10.5%, respectively.The results of a sample of size 5 taken over the last 5 hours included the following 4 data points and the sample average: 81, 74, 83, 66, x̄ = 79 . If the guideline is to maintain the product’s moisture within 1 standard deviation of the historic average, the number of sample values outside these limits is:a. 3b. 2c. 1d. none