You want to estimate the mean amount of time Internet users spend on Facebook each month. How many Internet users must be surveyed in order to be 95% confident that your sample mean is within 15 minutes of the population mean? Based on results from a prior Nielsen survey, assume that the standard deviation of the population of monthly times spent on Facebook is 210 min. 249 753 1267 898 1432

You want to estimate the mean amount of time Internet users spend on Facebook each month. How many Internet users must be surveyed in order to be 95% confident that your sample mean is within 15 minutes of the population mean? Based on results from a prior Nielsen survey, assume that the standard deviation of the population of monthly times spent on Facebook is 210 min. 249 753 1267 898 1432

Essentials of Business Analytics (MindTap Course List)

2nd Edition

ISBN:9781305627734

Author:Jeffrey D. Camm, James J. Cochran, Michael J. Fry, Jeffrey W. Ohlmann, David R. Anderson

Publisher:Jeffrey D. Camm, James J. Cochran, Michael J. Fry, Jeffrey W. Ohlmann, David R. Anderson

Chapter6: Statistical Inference

Section: Chapter Questions

Problem 3P: A simple random sample of 5 months of sales data provided the following information: a. Develop a...

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Assume that the traffic to the web site of Smileys People, Inc., which sells customized T-shirts, follows a normal distribution, with a mean of 4.5 million visitors per day and a standard deviation of 820,000 visitors per day. a. What is the probability that the web site has fewer than 5 million visitors in a single day? b. What is the probability that the web site has 3 million or more visitors in a single day? c. What is the probability that the web site has between 3 million and 4 million visitors in a single day? d. Assume that 85% of the time, the Smileys People web servers can handle the daily web traffic volume without purchasing additional server capacity. What is the amount of web traffic that will require Smileys People to purchase additional server capacity?
The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the standard deviation is 1.2 hours and that the number of hours of sleep follows a bell-shaped distribution. a. Use the empirical rule to calculate the percentage of individuals who sleep between 4.5 and 9.3 hours per day. b. What is the z-value for an adult who sleeps 8 hours per night? c. What is the z-value for an adult who sleeps 6 hours per night?
The Economic Policy Institute periodically issues reports on wages of entry-level workers. The institute reported that entry-level wages for male college graduates were $21.68 per hour and for female college graduates were $18.80 per hour in 2011. Assume that the standard deviation for male graduates is $2.30, and for female graduates it is $2.05. What is the sampling distribution of for a random sample of 50 male college graduates? What is the sampling distribution of for a random sample of 50 female college graduates? In which of the preceding two cases, part (a) or part (b), is the standard error of smaller? Why?
The president of Doerman Distributors, Inc., believes that 30% of the firm’s orders come from first-time customers. A random sample of 100 orders will be used to estimate the proportion of first-time customers. Assume that the president is correct and p = 0.30. What is the sampling distribution of for this study?
For the Hawkins Company, the monthly percentages of all shipments received on time over the past 12 months are 80, 82, 84, 83, 83, 84, 85, 84, 82, 83, 84, and 83. Construct a time series plot. What type of pattern exists in the data? Compare a three-month moving average forecast with an exponential smoothing forecast for α = 0.2. Which provides the better forecasts using MSE as the measure of model accuracy? What is the forecast for next month?
You may need to use the appropriate appendix table or technology to answer this question. A government agency provides the number of miles that residents of the 75 largest metropolitan areas travel per day in a car. Suppose that for a simple random sample of 50 City A residents the mean is 22.9 miles a day and the standard deviation is 8.7 miles a day, and for an independent simple random sample of 40 City B residents the mean is 18.6 miles a day and the standard deviation is 7.7 miles a day. (a) What is the point estimate of the difference between the mean number of miles that City A residents travel per day and the mean number of miles that City B residents travel per day? (Use City A − City B.) __________ mi/day
A simple random sample of 5 months of sales data provided the following information: a. Develop a point estimate of the population mean number of units sold per month. b. Develop a point estimate of the population standard deviation.
. MyApp is a small but growing startup that sees demand for several of its apps increasequickly. For the last six months, monthly downloads were 235,000, 290,000, 336,000,390,000, 435,000, and 498,000. Using a forecast for the first month of 220,000, aninitial trend forecast of 40,000, and smoothing parameters of 0.25 for both demandsmoothing and trend smoothing, forecast the demand for the next month using doubleexponential smoothing.
A business school has a goal that the average number of years of work experience of its MBA applicants is more than three years. Historical data suggest that the variance has been constant at around six months, and thus, the population variance can be assumed to be known. Based on last year’s applicants, it was found that among a sample of 47, the average number of years of work experience is 3.1. Can the school state emphatically that it is meeting its goal? Formulate the appropriate hypothesis test and con-duct the test.
A business school has a goal that the average number of years of work experience of its MBA applicants is more than three years. Historical data suggest that the variance has been constant at around six months, and thus, the population variance can be assumed to be known. Based on last year’s applicants, it was found that among a sample of 47, the average number of years of work experience is 3.1. Can the school state emphatically that it is meeting its goal? Formulate the appropriate hypothesis test and con-duct the test. (Show In Excel)
A new marketing campaign is being released by Pepsico to promote their Rockstar engergy drink line this summer and is expecting an increase in sales volume. Currently daily sales average $1,511.71 with a standard deviation of $14.466. Daily sales figures are compiled in a dataset and to forecast the change, 40.69 is added to every observation in the dataset. What is the new mean for daily sales?
In this chapter we showed how a simple random sample of 30 EAI employees can be used to develop point estimates of the population mean annual salary, the population standard deviation for annual salary, and the population proportion having completed the management training program. a. Use Excel to select a simple random sample of 50 EAI employees. b. Develop a point estimate of the mean annual salary. c. Develop a point estimate of the population standard deviation for annual salary. d. Develop a point estimate of the population proportion having completed the management training program.