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A random sample of 36 waiting times, T, will be taken from a system where the mean waiting time is assumed to be 100 hours and the standard deviation waiting time is assumed to be 12 hours. If these
You may use the manual method of calculation, or show how MegaStat (or other software) is used to analyze the data. Be sure to discuss the interpretation of results.
A researcher wants to create a 99% confidence interval for the population mean. He has a sample of n=120, an x-bar of $340, and a sample standard deviation of $122. What is the margin of error?
A company conducts a survey of its employees by taking a sample to determine what proportion would vote for or vote against a proposed pay increase. 320 would vote FOR while 1280 would vote against
The mean life span of the sample is 955 hours and the standard deviation is 35 hours. Is the company making acceptable light bulbs? Assume life spans are normally distributed.
. CRA CDs, Inc., wants the mean lengths of the "cuts" on a CD to be 135 seconds (2 minutes and 15 seconds). This will allow the disk jockeys to have plenty of time for commercials within each 10-min
A random sample of 25 days' receipts is chosen for an audit. What is the probability that the sample mean is larger than $2,220?
You are the shipping manager at the postham company you are interested in the percentage of packages delivered damaged a simple random sample of 500 packages yiields 16 delivered damaged and 484 de
In a survery of 2480 golfers, 15% said they were left-handed. The survery's margin of error was 3%. Find the confidence interval for p.
The quality-control inspector of a production plant will reject a batch of syringes if two or more defective syringes are found in a random sample of ten syringes taken from the batch. Suppose the b
Based on an SRS of 50 pineapples with a mean weight of 31.6 ounces, did the new irrigation system cause an increase in the mean weights of pineapples produced? Explain your answer completely.
Use the information in the FTC study to estimate p for the binomial experiment.
a statistics professor plans classes so carefully that the lenghts of her classes are uniformly distributed between 50.0 and 52.0 minutes. find the probability that a given class period runs less th
Fix-It Copiers advertises a mean time of 100 minutes for office calls with a standard deviation of 25 minutes. What percentage of calls are completed:
Compute a 90% confidence interval of the mean for a Weschler intellegence test with mean of 100.00 and standard deviation of 15.00 for a sample of 100 people. Use two decimal places.
A farmer loses $50,000 when the summer is too dry and makes $100,000 when the growing season is moderate. The probability of the growing season being too dry is 35%. What is the expectation for pro
Assume that the number of calories in 12-ounce soda cans is normally distributed. State the null and alternative hypotheses to test the manufacturer claim.
. Let the random variable Y measure the number of gallons (measured in thousands of gallons) that this gas station sells per week. If Y = 340 - 90X, what is the expected value of the random variable
Osteoporosis is a condition in which the bones become brittle due to loss of minerals. What percent of healthy young adults has osteoporosis by the WHO criterion?
A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.Determine the number of boxes,x,where 80% of the
According to the world factbook, 2004, the total fertility rate (estimated mean number of children born per woman) for Madagascar is 5.7. What is the standard deviation of this sampling distribution
Assume that the standard deviation of scores in the population of all male hotel managers is the same as the σ = 0.78 for the adult male population. Use a 1% alpha level. Show the
What value would you expect to find for the mean of all these sample means? What shape would you expect the distribution of all these sample means to have?
The mean weight of loads of rock is 45.0 tons with a standard deviation of 12.0 tons. If 16 loads are chosen at random for a weight check, find the probability that the mean weight of those loads i
Find the z-score for each student. Assuming both tests measure the same kind of ability, which student had the higher score?