An electrical firm manufactures light bulbs that have a length life with normal distribution, and a standard deviation of σ = 10 hours. A sample of size n = = 100 is obtained, and its sample mean is calculated to be 330 hours. x = Find the 95% confidence interval for the average length life μ. (328.04,331.96) Find the upper 95% bound for the average length life μ. 331.96 notation. ☑ invalid interval Find the lower 95% bound for the average length life μ. 328.04 notation. ☑ invalid interval Give your answer as intervals. Use -∞ and +∞ if needed.

A sample is selected from a population withu = 50. After a treatment is administered to the 16 individuals in the sample, the mean is found to be M = 55 and the standard deviation is s = 8, What is the test statistic for the sample mean?

A survey taken several years ago found that the average time a person spent reading the local daily newspaper was 10.8 minutes. The standard deviation of the population was 3 minutes. To see whether the average time had changed since the newspaper's format was revised, the newspaper editor surveyed 37 individuals. The average time that the 37 people spent reading the paper was 12.3 minutes. At =α0.01 , is there a change in the average time an individual spends reading the newspaper? Find the 99% confidence interval of the mean.     Find the 99% confidence interval of the mean. Round the answers to nearest whole number.     <<μ

Biological oxygen demand (BOD) is a pollution index that is monitored in the treated effluent of paper mills. A certain paper mill has taken 31 samples over the past 3 months. The mean and standard deviation for the sample data are 3.42 and 0.728 ppm respectively. The mill would like to see if this sample indicates that the true average BOD in their treated effluent exceeds the targeted 3.00 ppm. Let ? = 0.05. A) The test statistic, (ttest), for this data set is: Note: Round your answer to the nearest hundredth.B) The p-value is: C) The statistical decision and corresponding English interpretation for this study are: Fail to reject Ha: conclude that the true BOD in treated effluent exceeds 3 ppmFail to reject Ho: we cannot conclude that the true BOD in treated effluent exceeds 3 ppm    Reject Ha: we cannot conclude that the true BOD in treated effluent exceeds 3 ppmReject Ho: conclude that the true BOD in treated effluent exceeds 3 ppm

A population has a mean µ = 161 and a standard deviation o = 20. Find the mean and standard deviation of the sampling distribution of sample means with sample size n = 56. The mean is = μx (Round to three decimal places as needed.) and the standard deviation is o- = X 3 X

A random sample of 70 observations produced a mean of 27.5 and a standard deviation of 3.26. Find a 90% confidence interval for               < U < (b) Find a 95% confidence interval for              < U < (c) Find a 99% confidence interval for              < U <

The mean test score for a simple random sample of n=100 students was =80. The population standard deviation of test scores is σ=15. Construct a 95% confidence interval for the population mean test score μ.

From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that age remains constant at around 2.1 years. A survey of 38 smokers of this generation was done to see if the mean starting age is at least 19. The sample mean was 18.1 with a sample standard deviation of 1.3. Do the data support the claim at the 5% level? (i) Alpha (Enter an exact number as an integer, fraction, or decimal.)? =

A random sample of 90 observations produced a mean of ?⎯⎯⎯=26.3 from a population with a normal distribution and a standard deviation ?=2.08.

A certain variable has a bell-shaped distribution with mean μ=176.16μ=176.16 and standard deviation σ=4.9σ=4.9. You observe a value of x=184x=184. Is this a TYPICAL value of the variable (within 2 standard deviations of the mean), or an UNUSUAL one (more than 2 standard deviations from the mean)?