The quality-control manager at a compact fluorescent light bulb (CFL) factory needs to determine whether the mean life of a large shipment of CFLS is equal to 7,535 hours. The population standard deviation is 840 hours. A random sample of 49 light bulbs indicates a sample mean life of 7,355 hours. a. At the 0.05 level of significance, is there evidence that the mean life is different from 7,535 hours? b. Compute the p-value and interpret its meaning c. Construct a 95% confidence interval estimate of the population mean life of the light bulbs. d. Compare the results of (a) and (c). What conclusions do you reach?

A supplier is selling lumber to a building supply company.  The building supply company requires that the overall length of a particular type of board measure between 95.9 and 96.1 inches. Before sending its next shipment, the supplier collects a large sample of boards and determines the mean length of the sample is 96.03 inches, with a standard deviation of 0.029 inches. What is the process capability index of the current process? Two decimal places.

A​ half-century ago, the mean height of women in a particular country in their 20s was 62.3inches. Assume that the heights of​ today's women in their 20s are approximately normally distributed with a standard deviation of 2.25inches. If the mean height today is the same as that of a​ half-century ago, what percentage of all samples of 29of​ today's women in their 20s have mean heights of at least 63.41 inches?

The lengths of nails produced in a factory are normally distributed with a mean of 3.343.34 centimeters and a standard deviation of 0.070.07 centimeters. Find the two lengths that separate the top 3%3% and the bottom 3%3%.

A recent report indicates that 2-year-old children from the well-educated suburban families watched an average of m=60 minutes of television each day. Assuming that the distribution of television-watching times is normal with a standard deviation of 25 minutes, find each of the following proportions. a. What proportion of 2- year-old children watch more than two hours of television each day? b. what proportion of 2-year-old children watch less than 30 minutes a day?

The Wall Street Journal reported that 33% of taxpayers with adjusted gross incomes between $30,000 and $60,000 itemized deductions on their federal income tax return. The mean amount of deductions for this population of taxpayers was $16.941. Assume that the standard deviation iso = $2942. Use z-table. a. What is the probability that a sample of taxpayers from this income group who have itemized deductions will show a sample mean within $176 of the population mean for each of the following sample sizes: 30, 50, 100, and 400? Round your answers to four decimals. n = 30 n = 50 n = 100 n = 400 b. What is the advantage of a larger sample size when attempting to estimate the population mean? Round your answers to four decimals. A larger sample - Select your answer the probability that the sample mean will be within a specified distance of the population mean. In this instance, the probability of being within +176 of µ ranges from for a sample of size 30 to for a sample of size 400. 0Icon…

An air condition company will spend an average of 64 minutes with a standard deviation of 19 minutes on a service call. Based on this, and assuming a normal distribution, 5% of service calls will take more than how much time to complete? Approximately 66.29 minutes O Approximately 32.75 minutes O Approximately 39.41 minutes O Approximately 95.25 minutes O Approximately 77.23 minutes

The concentration of blood hemoglobin in middle-aged adult females is normally distributed with a mean of 13.5 g/dL and a standard deviation of 0.86 g/dL. Determine the hemoglobin levels corresponding to the: 90th percentile Middle 85% of middle-aged adult female hemoglobin levels

The president of a college wants to determine the mean number of units that college students take per semester. How large of a sample is required in order to be 99% sure that a sample mean will be off by no more than 1.25 units? An initial study suggested that the standard deviation is approximately 2.1 units.

The mean cholesterol level for females in a population is 200 with a standard deviation of 25. Samples of size 64 are drawn from the population.  A. What is the mean of the sample means? B. What is the standard error of the sample means?