An efficiency expert wants to determine the aver-age amount of time it takes a pit crew to change a set of four tires on a race car. Use the formula for n in Exercise 11.6 to determine the sample size that is needed so that the efficiency expert can assert with probability 0.95 that the sample mean will differ from µ, the quantity to be estimated, by less than 2.5 seconds. It is known from previous studies that σ = 12.2 seconds.
Answer to relevant QuestionsIn a study of television viewing habits, it is desired to estimate the average number of hours that teenagers spend watching per week. If it is reasonable to assume that σ = 3.2 hours, how large a sample is needed so that ...A study of two kinds of photocopying equipment shows that 61 failures of the first kind of equipment took on the average 80.7 minutes to repair with a standard deviation of 19.4 minutes, whereas 61 failures of the second ...Among 100 fish caught in a certain lake, 18 were inedible as a result of chemical pollution. Construct a 99% confidence interval for the corresponding true proportion. With reference to Exercise 11.30, construct a 95% confidence interval for the true variance of the skull length of the given species of bird. In exercise The length of the skulls of 10 fossil skeletons of an extinct species ...The following are the compressive strengths (given to the nearest 10 psi) of 30 concrete samples. Use a computer program to find a 90% confidence interval for the standard deviation of these compressive strengths.
Post your question