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- 1. QNT 275 Week 2 Homework Problem Set Excel File For more course tutorials visit www.tutorialrank.com 1. In a hearing test, subjects estimate the loudness (in decibels) of a sound, and the results are: 69, 67, 71, 72, 65, 75, 68, 68, 83, 73, 68. Calculate the measures of central tendency (Mean, median, mode) and the measures of dispersion (range, standard deviation, variance). 2.
- 2. The local amusement park was interested in the average wait time at their most popular roller coaster at the peak park time (2 p.m.). They selected 13 patrons and had them get in line between 2 and 3 p.m. Each was given a stopwatch to record the time they spent in line. The times recorded were as follows (in minutes). 117, 123, 110, 117, 99, 120, 148, 118, 119, 120, 45, 130, 118 What is the 72d percentile? 3. The average life of Canadian women is 73.90 years, and the standard deviation of the life expectancy of Canadian women is 9 years. Based on Chebyshev's Theorem, determine the upper and lower bounds on the
- 3. average life expectancy of Canadian women such that at least 95 percent of the population is included if the sample size is 100 women. 4. The local amusement park was interested in the average wait time at their most popular roller coaster at the peak park time (2 p.m.). They selected 13 patrons and had them get in line between 2 and 3 p.m. Each was given a stopwatch to record the time they spent in line. The times recorded were as follows (in minutes): 118, 121, 114, 116, 110, 120, 145, 118, 119, 121, 45, 135, 118. Calculate the measures of central tendency (Mean, median, mode) and the measures of dispersion (range, standard deviation, variance). 5.
- 4. The average lateness for one of the top airline companies is 10 minutes. The variance of the lateness measure is calculated as 8. An airplane arrived 12 minutes after the stated arrival time. Calculate the z-score for the lateness of this particular airplane. 6. According to a survey of the top 15 employers in a major city in the Midwest, a worker spends an average of 400 minutes a day on the job. Suppose the standard deviation is 20 minutes and the time spent is approximately a normal distribution. What are the times within which approximately 99.73 percent of all workers will fall? 7.
- 5. Recently an advertising company called 200 people and asked them to identify the company that was in an ad running nationwide. The following results were obtained. What percentage of those surveyed could not correctly recall the company? 8. A local electronics retailer recently conducted a study on purchasers of large screen televisions. The study recorded the type of television and the credit account balance of the customer at the time of purchase. They obtained the following results. What percentage of purchases were plasma televisions by customers with the smallest credit balances? 9.
- 6. The following is a partial relative frequency distribution of grades in an introductory statistics course. Find the relative frequency for the B grade. 10 A CFO is looking at what percentage of a company's resources are spent on computing. He samples companies in the pharmaceutical industry and develops the following stem-and-leaf graph. What would be the class length used in creating a frequency histogram? ..................................................................................................................... ......................................... QNT 275 Week 3 Homework Problem Set Excel File For more course tutorials visit www.tutorialrank.com 1.
- 7. A survey is made in a neighborhood of 90 voters. 75 are Democrats and 15 are Republicans. Of the Democrats, 30 are women, while 7 of the Republicans are women. If one subject from the group is randomly selected, find the probability the individual is a male Republican. 2. Container 1 has 8 items, 3 of which are defective. Container 2 has 5 items, 3 of which are defective. If one item is drawn from each container, what is the probability that only one of the items is defective? 3. A letter is drawn from the alphabet of 26 letters. What is the probability that the letter drawn is a vowel?
- 8. 4. A family has two children. What is the probability that both are girls, given that at least one is a girl? 5. If n = 29 and p = .6, then the standard deviation of the binomial distribution is
- 9. 6. Consider a Poisson distribution with an average of 4 customers per minute at the local grocery store. If X = the number of arrivals per minute, find the probability of more than 6 customers arriving within a minute. 7. An important part of the customer service responsibilities of a cable company is the speed with which trouble in service can be repaired. Historically, the data show that the likelihood is 0.70 that troubles in a residential service can be repaired on the same day. For the first four troubles reported on a given day, what is the probability that all four will be repaired on the same day?
- 10. 8. Suppose that the waiting time for a license plate renewal at a local office of a state motor vehicle department has been found to be normally distributed with a mean of 29 minutes and a standard deviation of 6 minutes. Suppose that in an effort to provide better service to the public, the director of the local office is permitted to provide discounts to those individuals whose waiting time exceeds a predetermined time. The director decides that 10 percent of the customers should receive this discount. What number of minutes do they need to wait to receive the discount? 9. An apple juice producer buys all his apples from a conglomerate of apple growers in one northwestern state. The amount of juice obtained from each of these apples is approximately normally distributed with a mean of 2.38 ounces and a standard deviation of 0.1 ounce. What is the probability that a randomly selected apple will contain more than 2.40 ounces? 10
- 11. While conducting experiments, a marine biologist selects water depths from a uniformly distributed collection that vary between 2.00 m and 8.00 m. What is the probability that a randomly selected depth is between 2.25 m and 5.00 m? ..................................................................................................................... ......................................... QNT 275 Week 4 Homework Problem Set Excel File For more course tutorials visit www.tutorialrank.com 1. A sample of 100 items has a population standard deviation of 5.9 and a mean of 32. Construct a 95 percent confidence interval for μ. 2. At the end of 1990, 1991, and 1992, the average prices of a share of stock in a portfolio were $34.75, $34.65, and $31.25 respectively. To
- 12. investigate the average share price at the end of 1993, a random sample of 75 stocks was drawn and their closing prices on the last trading day of 1993 were observed with a mean of 33.78 and a standard deviation of 14.25. Estimate the average price of a share of stock in the portfolio at the end of 1993 with a 90 percent confidence interval. 3. A research study investigated differences between male and female students. Based on the study results, we can assume the population mean and standard deviation for the GPA of male students are µ = 3.3 and σ = 0.3. Suppose a random sample of 1200 male students is selected and the GPA for each student is calculated. Find the interval that contains 90 percent of the sample means for male students. 4. A manufacturing company measures the weight of boxes before shipping them to the customers. If the box weights have a population mean of 80 lb and standard deviation of 6 lb, respectively, then based on a sample size of 100 boxes, what is the probability that the average weight of the boxes will exceed 83 lb?
- 13. 5. A random sample of size 100 is taken from a population with mean 64 and standard deviation 5.2. Find P(x bar < 60).