Exam 19: Questions that Involve Online Topics

Based on past experience,only 0.5% of the invoices of a company contain an error.Out of the 1,500 invoices that the company will issue,what is the approximate probability that zero invoices will contain an error?

TABLE 8-2 A wealthy real estate investor wants to decide whether it is a good investment to build a high-end shopping complex in a suburban county near Chicago.His main concern is the total market value of the 3,605 houses in the suburban county.He commissioned a statistical consulting group to take a sample of 200 houses and obtained a sample mean market price of $225,000 and a sample standard deviation of $38,700.The consulting group also found out that the mean differences between market prices and appraised prices was $125,000 with a standard deviation of $3,400.Also the proportion of houses in the sample that are appraised for higher than the market prices is 0.24. -Referring to Table 8-2,if the investor wants a 95% confidence on estimating the true population mean market price of the houses in the suburban county to be within $10,000,how large a sample will he need?

Using the hat matrix elements hᵢ to determine influential points in a multiple regression model with k independent variable and n observations,Xᵢ is an influential point if

One of the reasons that a correction for continuity adjustment is needed when approximating the binomial distribution with a normal distribution is because the probability of getting a specific value of a random variable is zero with the normal distribution.

TABLE 19-4 A stock portfolio has the following returns under the market conditions listed below. Market Condition Probability Return Bull 0.4 $200 Stable 0.3 $100 Bear 0.3 -$100 -Referring to Table 19-4,what is the coefficient of variation?

TABLE 9-1 A manufacturer produces light bulbs that have a mean life of at least 500 hours when the production process is working properly.Based on past experience,the population standard deviation is 50 hours and the light bulb life is normally distributed.The operations manager stops the production process if there is evidence that the population mean light bulb life is below 500 hours. -Referring to Table 9-1,if you select a sample of 100 light bulbs and are willing to have a level of significance of 0.01,the probability of the operations manager stopping the process if the population mean bulb life is 490 hours is ________.

TABLE 9-3 A drug company is considering marketing a new local anesthetic.The effective time of the anesthetic the drug company is currently producing has a normal distribution with a mean of 7.4 minutes with a standard deviation of 1.2 minutes.The chemistry of the new anesthetic is such that the effective time should be normally distributed with the same standard deviation.The company will market the new local anesthetic as being better if there is evidence that the population mean effective time is greater than the 7.4 minutes of the current local anesthetic. -Referring to Table 9-3,if you select a sample of 25 new local anesthetics and are willing to have a level of significance of 0.1,the confidence coefficient of the test is ________ if the population mean effective time is 8 minutes.

As a general rule,one can use the normal distribution to approximate a binomial distribution whenever nπ and n(π - 1)are at least 5.

For a given level of significance,if the sample size is increased but the summary statistics remain the same,the probability of committing a Type I error will increase.

TABLE 16-1 Given below are the average prices for three types of energy products for five consecutive years. -Referring to Table 16-1,what are the simple price indices for electricity,natural gas and fuel oil,respectively,in year 1 using year 5 as the base year?

TABLE 7-2 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random samples of size 50 are selected from a population of 900.Use the finite population correction factor. -Referring to Table 7-2,what is the probability that a random sample of 50 will have at least 30% of customers who will make a purchase after visiting the website?

TABLE 7-2 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random samples of size 50 are selected from a population of 900.Use the finite population correction factor. -Referring to Table 7-2,the standard error of all the sample proportions of customers who will make a purchase after visiting the website is ________.

TABLE 7-1 Times spent studying by students in the week before final exams follow a normal distribution with standard deviation 8 hours.A random sample of 4 students was taken from a population of 50 in order to estimate the mean study time for the population of all students.Use the finite population correction. -Referring to Table 7-1,what is the standard error of all the sample means?

TABLE 19-2 The following payoff matrix is given in dollars. -Referring to Table 19-2,what is the optimal action using the EMV criterion?

TABLE 19-1 The following payoff table shows profits associated with a set of 3 alternatives under 2 possible states of nature. -Blossom's Flowers purchases roses for sale for Valentine's Day.The roses are purchased for $10 a dozen and are sold for $20 a dozen.Any roses not sold on Valentine's Day can be sold for $5 per dozen.The owner will purchase 1 of 3 amounts of roses for Valentine's Day: 100,200,or 400 dozen roses.If the probability of selling 100 dozen roses is 0.2 and 200 dozen roses is 0.5,then the probability of selling 400 dozen roses is

TABLE 19-3 The following information is from 2 investment opportunities. -Referring to Table 19-3,which investment has the optimal return to risk ratio?

TABLE 6-1 A company has 125 personal computers.The probability that any one of them will require repair on a given day is 0.15. -Referring to Table 6-1 and assuming that the number of computers that requires repair on a given day follows a binomial distribution,compute the probability that there will be less than 8 computers that require repair on a given day using a normal approximation.

A company that manufactures designer jeans is contemplating whether to increase its advertising budget by $1 million for next year.If the expanded advertising campaign is successful,the company expects sales to increase by $1.6 million next year.If the advertising campaign fails,the company expects sales to increase by only $400,000 next year.If the advertising budget is not increased,the company expects sales to increase by $200,000.Identify the outcomes in this decision-making problem.

TABLE 9-2 An appliance manufacturer claims to have developed a compact microwave oven that consumes a population mean of no more than 250 W.From previous studies,it is believed that power consumption for microwave ovens is normally distributed with a population standard deviation of 15 W.If there is evidence that the population mean consumption is greater than 250 W,the manufacturer will be unable to make the claim. -Referring to Table 9-2,if you select a sample of 20 compact microwave ovens and are willing to have a level of significance of 0.10,the power of the test is ________ if the mean power consumption of all such microwave ovens is in fact 248 W.

The curve for the ________ will show a rapid increase in utility for initial amounts of money followed by a gradual leveling off for increasing dollar amounts.