Tom wants to estimate the percentage of students who live more than 3 miles from the school.He wants to create a 95% confidence interval which has a margin of error of at most 3% .How many students must be polled to create the confidence interval?

High-power experimental engines are being developed by the Stevens Motor Company for use in its new sports coupe. The engineers have calculated the maximum horsepower for the engine to be 810HP . Sixteen engines are randomly selected for horsepower testing. The sample has an average maximum HP of 890 with a standard deviation of 85HP . Assume the population is normally distributed. Step 1 of 2 :  Calculate a confidence interval for the average maximum HP for the experimental engine. Use a significance level of α=0.01 . Round your answers to two decimal places.

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

High-power experimental engines are being developed by the Stevens Motor Company for use in its new sports coupe. The engineers have calculated the maximum horsepower for the engine to be 600HP600⁢HP. Nine engines are randomly selected for horsepower testing. The sample has an average maximum HP of 610610 with a standard deviation of 50HP50⁢HP. Assume the population is normally distributed.   Step 1 of 2 :   Calculate a confidence interval for the average maximum HP for the experimental engine. Use a significance level of α=0.05�=0.05. Round your answers to two decimal places.

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 study was designed to compare the attitudes of two groups of nursing students towards computers. Group 1 had previously taken a statistical methods course that involved significant computer interaction. Group 2 had taken a statistic methods course that did not use computers. The students' attitudes were measured by administering the Computer Anxiety Rating Scale (CARS). A random sample of 1010 nursing students from Group 1 resulted in a mean score of 55.755.7 with a standard deviation of 7.97.9. A random sample of 1515 nursing students from Group 2 resulted in a mean score of 65.665.6 with a standard deviation of 6.16.1. Can you conclude that the mean score for Group 1 is significantly lower than the mean score for Group 2? Let μ1�1 represent the mean score for Group 1 and μ2�2 represent the mean score for Group 2. Use a significance level of α=0.05�=0.05 for the test. Assume that the population variances are equal and that the two populations are normally distributed. Step 3 of 4:…

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

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?