The diameter of a spindle in a small motor pool is supposed to be 5 millimeters.  If the spindle is too large or too small, the motor will not perform properly.  The manufacturer measures the diameter in a sample of 225 motors and calculates the sample mean diameter as 4.89 millimeters.  We wish to test if the mean diameter is 5 millimeters.  Which of the following are the appropriate null and alternative hypotheses, letting μ denote the average diameter of all spindles?   The null hypothesis is H0:                             ["", "", "", ""]            The alternative hypothesis is Ha:

We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately σ=79.4σ=79.4. We would like to be 99% confident that the estimate is within 0.5 of the true population mean. How large of a sample size is required?n=

I didnt mean to select an option on the second portion but I need help solving this.

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=72.1σ=72.1. You would like to be 99% confident that your estimate is within 2 of the true population mean. How large of a sample size is required?

In the entire population of a certain type of tree, the mean height of the trees is μ = 168.8 ft and the standard deviation is σ = 43.6 ft. You collect a random sample of n=22 trees. The distribution of these sample means is shown below. Each tick mark on the horizontal axis is a distance of one more standard error. Complete the indicated boxes, correct to two decimal places. mean of distribution=168.8 standard error=9.30   Note: The left box is 2 standard errors below the mean. The middle box is the mean. The right box is 2 standard errors above the mean.

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=37.8σ=37.8. You would like to be 90% confident that your estimate is within 1 of the true population mean. How large of a sample size is required?

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=56.5σ=56.5. You would like to be 95% confident that your estimate is within 1 of the true population mean. How large of a sample size is required?

In a random sample of 765 adults in the United States, 122 of them said if they had to cover a $400 emergency expense, they would need to use a credit card and pay it back over time.  a. what is the parameter being estimated b. what is the sample proportion (must show work)

A researcher is studying how much electricity (in kilowatt hours) people from two different cities use in their homes. Random samples of 11 days from Tampa (Group 1) and 16 days from New York City (Group 2) are shown below. Test the claim that the mean number of kilowatt hours in Tampa greater than the mean number of kilowatt hours in New York City. Use a significance level of a = 0.10. Assume the populations are approximately normally distributed with unequal variances. Round answers to 4 decimal places. Tampa New York City 1015.4 1010 1010.3 1022.8 1001.7 1028.9 1001.7 1026.9 1022.6 1001.7 1020.2 1012.4 1021.9 1015.9 1018.9 1005.8 996.2 1006.1 1010.5 1012 1005.1 1025.9 1005.6 1020.2 985.3 994.9 1013.2 What are the correct hypotheses? Note this may view better in full screen mode. Select the correct symbols for each of the 6 spaces. Ho: Select an answer ✓ ? Select an answer ✓ H₁: Select an answer ✓ ? ✓ Select an answer ✓

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=44.7σ=44.7. You would like to be 95% confident that your estimate is within 3 of the true population mean. How large of a sample size is required?