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They select a random sample of 525 employment records, and find that 229 of the people are females. State the conditions needed to build a confidence interval.
A shipment of 40 computers contains five that are defective. How many ways can a small business buy three of these computers and receive no defective ones?
A professor recorded scores from a 5-point quiz for each student in an introductory psychology class. If the data are presented in a frequency distribution graph, what type of graph should be used?
The time required to make 900 gallons of synthetic rubber at a plant in South America in a recent year was normally distributed with a mean of 15 hours and a standard deviation of 2.5 hours. What is
(A) Find the 95% confidence interval of the mean score for all 50 golfers. (B) Find the 95% confidence interval of the mean score for all golfers if this is a sample of 80 golfers instead of a sampl
The annual rice yield (in pounds), is given by the equation y-hat = 859 + 5.76a + 3.82b, where ‘a' is the number of acres planted (in thousands), and ‘b' is the number of acres harvested
No children that is equal to the value obtained by the census. Give the z statistic (rounded to two decimal places) and the P-value. What do you conclude?
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. The 100 filings showed an average preparati
Is there evidence to support, or to reject the claim at the alpha = 0.02 level? Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtai
A random sample of 4000 Canadian citizens yielded 2250 who are in favor of gun control legislation. Estimate the true proportion of all Americans who are in favor of gun control legislation using a
A hospital is hoping to introduce a Fast Care Unit. The hospital claims that after the initial run, 87% of the patients were pleased with the service. We ask 20 randomly selected patients whether or
When an emergency situation does not exist, the alarm sounds with a probability of 0.02. A real emergency situation is a rare event, with a probability 0.004. Given that the alarm has just sounded,
To help consumers assess the risks they are taking, the Food and Drug Administration (FDA). The sample standard deviation is less than the degrees of freedom.
Does all data have a mean, median, or mode? Explain why or why not. When is the mean the best measure of central tendency? When is the median the best measure of central tendency?
A questionnaire will be published and the first 1000 completed questionnaires will be analyzed. Which of the following errors will be associated with the sample?
A legal researcher is studying the age distribution of juries by comparing them with the overall age distribution of available jurors.
The average monthly gasoline purchase for a family with 2 cars is 90 gallons. This statistic has a normal distribution with a standard deviation of 10 gallons. A family is chosen at random.
How many boys and girls are needed to ensure that a 95% confidence interval estimate for the differncein mean BMI between boys and girls has a margin of error not exceeding 2 units?
Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results
A researcher claims that the average age of people who buy lottery tickets is 70. A sample of 30 is selected and their ages are recorded as shown below. The standard deviation is 16. At alpha = 0.05
The average amount of insulation in the sample of household is 12 inches. The sample standard deviation is 15 inches. Set up and interpret a 95% confidence interval.
A marketing firm wants to estimate the average amount spent by patients at the hospital pharmacy. For a sample of 200 randomly selected patients, the mean amount spent was $92.75 and the standard de
In conducting a hypothesis test to see if there is evidence that the population mean is less than 220, using a .03 significance level what will be your critical value?
A drug manufacturer wants to estimate the mean heart rate for patients with a certain heart condition. Because the condition is rare, the manufacturer can only find 15 people with the condition curr
The heights of 10 sixth graders are listed in inches: {53, 61, 54, 60, 58, 62, 55, 58, 59, 56}. Find the mean, median, mode, sample variance, and range.