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A researcher gathered 15 data points which seem to be reasonably bell shaped. Which distribution should the researcher use to compute confidence intervals?
In testing the claim regarding a population mean when sigma is unknown we
The table below shows the breakdown of actual status versus medical test results for a rare disease where n = 100,000.
An insurance company expects 10% of its policyholders to collect claims of $400 this year and the remaining 90% to collect no claims. The variable is the amount they will pay in claims per person.
An automobile finds that 1 in every 2000 automobile produced has particular manufacturing defect. Use a binomial distribution to find the probability of finding 4 cars with the defect in a random samp
When a new drug is formulated, the pharmaceutical company should subject is to lengthy and involved testing before receiving the necessary permission from the Food and Drug Administration (FDA) to m
An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings.
At a particular university it has been found that 20% of the students withdraw without completing the introductory statistics course. Assume that 20 students have registered for the course this quar
In a survey of 552 U.S. businesses, 400 of such companies indicated that they monitor employees' web site visits. For purposes of this exercise, suppose that it is reasonable to regard this sample
Consider Bernoulli trials with success probability p= 0.3. Determine the probability that four trials results in all failures.
The trade magazine Quality Progress published a study of subscribers' salaries. The 223 vice presidents sampled had a mean salary of $116,754 and a standard deviation of $39,185. Suppose the goal of
The CEO of a Canadian company wants to estimate the proportion of Canadians who own their own home. What sample size should be obtained if he wants the estimate to be within E = 0.02with 90% confide
In order to test for significance of a regression model involving 8 independent variables and 121 observations, the numerator and denominator degrees of freedom (respectively) for the critical value
In multiple regression analysis SSR = 1,000 and SSE = 200. The F statistic for this model is
In a regression analysis, the coefficient of correlation is 0.16. The coefficient of determination in this situation is
For the most current year available, the mean annual cost to attend a private university in the United States was $20,307. Assume the distribution of annual costs follows the normal probability distr
Suppose that the mean hourly cost to operate commercial airplane follows the normal distribution with a mean of $2,350 per hour and a standard deviation of $205.
Among U.S. cities with a population of more than 250,000 the mean one-way commute to work is 24.3 minutes. The longest one-way travel time is New York City, where the mean time is 38.2 minutes. Assu
A researcher plans to develop a test of hypotheses at the ? = 0.10 significance level. She designs her study to have a power of 0.70 at a particular alternative value of the parameter of interest.
In studies of worker productivity, it has been noticed that any change in the work environment together with knowledge that a study is underway, will produce a short-term increase in productivity. T
In assessing the validity of any test of hypotheses, it is good practice to
An instructor wanted to develop a confidence interval for the mean GPA of the students in his class. He used the campus records system to obtain all their GPA's and computed the 95% interval as (2.3
The most significant condition for sound conclusions from statistical inference is usually
Emissions of sulfur dioxide by industry set off chemical changes in the atmosphere that result in "acid rain." The acidity of liquids is measured by pH on a scale of 0 to 14.
Determine the margins of error for 95% confidence based on SRSs of 400 young women and 1600 young women.