n Northern Yellowstone Lake, earthquakes occur at a mean rate of 1.2 quakes per year. LetXbe the number of quakes in a given year.

What is the probability of fewer than three quakes?(Round your answer to 4 decimal places.)

Probability

(c)What is the probability of more than five quakes?(Round your answer to 4 decimal places.)

On average, 2 percent of all persons who are given a breathalyzer test by the state police pass the test (blood alcohol under .08 percent). Suppose that 500 breathalyzer tests are given.

(a)What is the expected number who pass the test?

Expected number

(b)What is the approximate Poisson probability that 5 or fewer will pass the test?(Round your answer to 4 decimal places.)

Poisson probability

Jim's systolic blood pressure is a random variable with a mean of 144 mmHg and a standard deviation of 24 mmHg. For Jim's age group, 140 is the threshold for high blood pressure.

Assume the data given follow the normal probability distribution.

(a)If Jim's systolic blood pressure is taken at a randomly chosen moment, what is the probability that it will be 134 or less?(Round yourz-value to 2 decimal places. Use Appendix C-2 to find probabilities. Round your final answer to 4 decimal places.)

Probability

(b)If Jim's systolic blood pressure is taken at a randomly chosen moment, what is the probability that it will be 179 or more?(Round yourz-value to 2 decimal places. Use Appendix C-2 to find probabilities. Round your final answer to 4 decimal places.)

Probability

(c)If Jim's systolic blood pressure is taken at a randomly chosen moment, what is the probability that it will be between 116 and 170?(Round your z-value to 2 decimal places. Use Appendix C-2 to find probabilities. Round your final answer to 4 decimal places.)

Probability

A certain airplane has two independent alternators to provide electrical power. The probability that a given alternator will fail on a one-hour flight is .02.

(a)What is the probability that both will fail?(Round your answer to 4 decimal places.)

Probability

(b)What is the probability that neither will fail?(Round your answer to 4 decimal places.)

Probability

(c)What is the probability that at least one fails?(Round your answer to 4 decimal places.)

Probability

The fracture strength of a certain type of manufactured glass is normally distributed with a mean of 512 MPa with a standard deviation of 14 MPa.

(a)What is the probability that a randomly chosen sample of glass will break at less than 512 MPa?(Round your answer to 2 decimal places.)

Probability

(b)What is the probability that a randomly chosen sample of glass will break at more than 536 MPa?(Round your answer to 4 decimal places.)

Probability

(c)What is the probability that a randomly chosen sample of glass will break at less than 541 MPa?(Round your answer to 4 decimal places.)

Probability

(a)A poll of 2,277 likely voters was conducted on the president's performance. Approximately what margin of error would the approval rating estimate have if the confidence level is 95%?(Round your answer to 4 decimal places.)

Margin of error

(b)The poll showed that 44% approved the president's performance. Construct a 90% confidence interval for the true proportion.(Round your answer to 4 decimal places.)

The 90%confidence intervalis fromto.

(c)Would you agree that the percentage of all voters who approve of the president's performance could be 50%?

multiple choice

• Yes, the confidence interval contains .50.
• No, the confidence interval does not contain .50.