A researcher desires to estimate the difference in means of two populations. To accomplish this, she takes a random sample of 81 items from the first population. The sample yields a mean of 168 with a variance of 324. A random sample of 64 items is taken from the second population yielding a mean of 161 with a variance of 625. C

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The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%. The population etiologic fraction of disease du

With a 90% confidence interval, what size sample would we need based on the proportion of population in proportion to sample size?
Null hypothesis: There is a taste difference between the two brands so consumers will be able to identify the difference in brand seventy percent of the time. The alternate null hypothesis assert

1. A medical test for HIV infection has three possible test results: positive ( ), negative ( ),
and inconclusive ( ). Given that a person is infected, the probabilities of these outcomes
are: 0.85, 0.10, and 0.05, respectively. Given that a person is not infected, the probabilities
of these outcomes are:

Roper ASW conducted a survey to learn about American adults' attitudes toward money and happiness. 56% of the respondents said they balance their checkbook at least once a month.
a. Suppose a sample of 400 American adults were taken. Show the sampling distribution of the proportion of adults who balance their checkbook at le

Consider the e-billing case. The mean and the standard deviation of the sample of n = 65 payment times are = 18.7598 and s = 3.9494. Test H0: μ = 19.1 versus Ha: μ < 19.1 by setting α equal to .01 and using a critical value rule and assume normality of the population. (Round your "t" and "t0.01" answers to 3 decimal places

The average cost of employing each police officer per year if $30,000 for a small twon. The current population of the town is 1,000. Calculate the per capita cost per police officer. Explain why the increase in population can result in increased per capita taxes, even though the per capita cost per police officer declines with p

If P is the population on the first day of the year, B is the birth rate, and D is the death rate, the estimated population at the end of the year is given by the formula:
P + (B * P)/100 - (D * P)/100
The population growth rate is given by the formula:
B - D
Write a program that prompts the user to enter the sta

A hotel has 90 rooms. Past experience shows that only 80% of people who reserve rooms actually show up. If the hotel takes 100 reservations, what is the chance there will be enough rooms for the people who actually show up? (Hint: You want to find the chance that, in the sample of 100 reservations, the percentage of those who sh