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Part 1 of 3 -

Question 1 of 20

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Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A marketing research consultant hired by Coca-Cola is interested in determining the proportion of customers who favor Coke over other soft drinks. A random sample of 400 consumers was selected from the market under investigation and showed that 53% favored Coca-Cola over other brands.

Compute a 95% confidence interval for the true proportion of people who favor Coke. Place your LOWER limit, rounded to 3 decimal places, in the first blank

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Question 9 of 20

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The average gas mileage of a certain model car is 26 miles per gallon. If the gas mileages are normally distributed with a standard deviation of 1.3, find the probability that a randomly selected car of this model has a gas mileage between 25.8 and 26.3 miles per gallon.

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Question 10 of 20

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Compute $f$P(t_{15}geq 2.0)f$$ where t₁₅has a t-distribution with 15 degrees of freedom.

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Question 11 of 20

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A sample of 23 European countries found that the variance of life expectancy was 7.3 years. What is the 95% confidence interval estimate for the variance of life expectancy in Europe?

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Question 12 of 20

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In order to be accepted into a top university, applicants must score within the top 5% on the SAT exam. Given that SAT test scores are normally distributed with a mean of 1000 and a standard deviation of 200, what is the lowest possible score a student needs to qualify for acceptance into the university?

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Question 13 of 20

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Find the 95% confidence interval for the standard deviation of the lengths of pipes if a sample of 26 pipes has a standard deviation of 10 inches.

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Question 14 of 20

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In constructing a confidence interval estimate for a population mean, when we replace $f$sigma f$$ with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is:

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Question 15 of 20

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If you increase the confidence level, the confidence interval ____________.

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Question 16 of 20

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Compute $f$P(t_{20}leq -0.95)f$$ where t₂₀has a t-distribution with 20 degrees of freedom.

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Question 17 of 20

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If you are constructing a confidence interval for a single mean, the confidence interval will___________ with an increase in the sample size.

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Question 18 of 20

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The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and $f$hat{p}f$$ = 0.20 is

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Part 3 of 3 -

Question 19 of 20

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A 90% confidence interval estimate for a population mean is determined to be 72.8 to 79.6. If the confidence level is reduced to 80%, the confidence interval becomes narrower.

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