The weekly earnings of middle managers in a large corporation are approximately normally distributed with a standard deviation of 36 dollars. A researcher wishes to estimate the mean weekly earnings. Find the sample size needed if she requires a 95% degree of confidence that the sample mean will not differ from the population by
8.48 A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in square millimeters) are shown below: 0
A random sample of n=31 households is asked the number of TV sets in the household. The responses are 1 0 2 3 2 3 4 2 1 1 2 4 3 2 3 3 0 1 0 1 3 2 4 3 2 1 4 0 1 2 3 What is the mean number of TVs? What is the standard deviation? What is the best estimate for the mean number of TVs for the population of all American househo
In a certain manufacturing process, the diameter of holes drilled in a steel plate is a normally distributed random variable. The process standard deviation is known to be s =0.005 cm. A sample of 15 plates shows a mean hole diameter of 2.475 cm. Find the 95 percent confidence interval for Mean (M).
I need help solving 95% confidence interval and point estimate problems. A sample of 16 people are used, each one is to keep track of their time with the following result in hours. 1.8, 1.7, 0.9, 1.1, 1.5, 1.5, 1.2, 0.6, 1.4, 0.9, 0.7, 1.8, 1.7, 2.2, 1.5, 1.3 Construct a 95% confidence interval for the amount of time n
Incomes in the thousands of dollars were sampled in one region, they are as follows (1.5, 3.0, 4.2, 5.6, 2.6, 4.1, 0.9, 5.7, 5.4, 2.6). Assume the population is normal. What is the point estimate of the population mean? What is the point estimate for the population variance? Assume the standard deviation of the populat
Always get overwhelmed by the amount of material when covered at a comprehensive level. Attached is the study material of what to be prepared to cover at the conclusion of this course. I have worked through them but get stumped at several points. Can you provide a systematic approach to these problems and provide a reference to
Always get overwhelmed by the amount of material when covered at a comprehensive level. Attached is the study material of what to be prepared to cover at the conclusion of this course. I have worked through them but get stumped at several points. Can you provide a systematic approach to these problems and provide a reference to
Solution to check against my work. You work for a consumer advocate agency and want to find the average repair cost of a washing machine. You randomly select 40 repair costs and find the average to be $100.00. The standard deviation is $17.50. a. Construct a 95% confidence interval for the average repair costs. b. W
I'd like assistance in solving the following problem. A major West Coast chain of "budget fare" hotels is planning an expansion into the mid-west. The mean rate for a single room at 50 "budget fare" hotels in the tri-city area of Columbus/Dayton/Cincinnati Ohio is $110.00 with a standard deviation of $15.00. a) Find
Please help with the following problem. Provide step by step calculations in Excel. 17. Consider a 98% confidence interval to estimate a population mean based on a sample of 625 observations with a sample mean of 425 and a sample standard deviation of 150. How many units wide would such a confidence interval be? 18. In a
Please see attached (The material is from Confidence Intervals For Variances. Please show each step of your solution. Thank you.)
A machine produces 3-inch nails. A sample of 100 nails is selected, and it is found that 25 are shorter than 3 inches. Find the 95% confidence interval on the proportion of all such nails that are shorter than 3 inches.
Find the confidence interval. Use the given confidence level and sample data to find a confidence interval for estimating the population mean. Amounts lost by gamblers who took a bus to an Atlantic City casino: 99% confidence; n = 40, = $189, and is known to be $87.
Refer to the accompanying Minitab display of a 95% confidence interval generated using the methods of this section. The sample display results from using a random sample of speeds of drivers ticketed on a section of Interstate 95 in Connecticut. Variable N Mean StDev SE Mean 95% CI Speed
1.) With a margin of error of 0.050; confidence level of 99% ^p and ^q unknown, what is the minimum sample size required to estimate a population proportion or percentage? 2.) Amounts lost by gamblers who took a bus to Atlantic City casino: 99% confidence; n=40, mean of values in sample = $189,standard deviation is known to b
Can you help me with two word problems on confidence intervals and formulas? *A sample of 20 pages was taken without replacement from the 1,591 page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored maps, text, etc)
1. A study was conducted to estimate the mean amount spent on birthday gifts for a typical family having two children. A sample of 150 was taken, and the mean amount spent was $225. Assuming a standard deviation equal to $50, find the 95% confidence interval for mu, the mean for all such families. 2. A 95% confidence interv
You are constructing a 95% confidence interval using the information: n = 60, = 65.5, s = 2.5, and E = 0.7. What is the value of the middle of the interval? A. 0.7 B. 2.5 C. 0.95 D. 65.5 What sample size would be needed to estimate the population mean to within one-half standard deviation with 95% confidence?
I need step-by-step instruction on the following problem: Use the sample data and confidence level to construct the confidence interval estimate of the population proportion of p. n=500, x=200 95% confidence I've worked through a portion of it but I don't understand how to look up and find the critical value in table A-
A researcher is interested in estimating the average salary of fire fighters in a large city. He wants to be 95% confident that his estimate is correct. If the standard deviation is $1050, how large a sample is needed to get the desired information and to be accurate within $200?
If 400 households have an annual average income of $50,000 with a standard deviation of $4,000, what is the 90% confidence interval that includes the population household income? Please show all steps of the work, so tht I can understand the formulas/process.
If 90 out of 120 people asked said they were in favor of cloning, what is the interval that would make you 99% confident that it includes the proportion of people in the entire population that would be in favor of cloning? Given the data in problem above, what sample size would you need to have in order to have a 95% confidence
A sample of the math test scores of 35 fourth-graders has a mean of 82 with a standard deviation of 15. Find the 95% confidence interval of the mean math test scores of all fourth-graders. Find the 99% confidence interval of the mean math test scores of all fourth-graders. Which interval is larger? Explain why.
1. Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. (a) Construct a 90 percent confidence interval for the proportion of all kernels that would not po
TRUE OR FALSE (With justification)? If in a probability distribution you got the sum of probabilities less than one, it may mean that you skipped some possible outcome/outcomes. Health insurance policies are set up in such a way that a healthy person has a negative expected value, and a sickly person has a positive one.
Please help with the following problem. A stationery store wants to estimate the total retail value of the 300 greeting cards that it has in its inventory. What are the upper and lower limits of the 95% confidence interval estimate of the population total value of all greeting cards that are in inventory if a random sample o
Don't quite understand the concept of computing confidence intervals. How would confidence intervals determine sampling design and data collection for information gathered.
Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. a) Construct a 90% confidence interval for the proportion of all kernels that would not pop. b)
I need to know how to: (a) Construct a 95 percent confidence interval for the true mean. (b) Why might normality be an issue here? (c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence? (d) If this is not a reasonable requirement, suggest one that is. A sample of