What statistic best estimates the population mean, μ?

A sociologist found that in a random sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1.

a. Find the best point estimate of the population mean. (This is a number. Do not round.)

A sociologist found that in a random sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1

.Find the 95% confidence interval of the mean number of jobs. Do not round the z value, it should have two decimal places, example 2.34. Round the interval to one decimal place, example 3.2 < μ < 5.6

z-value from the table for the formula:

Z-interval:

[x] < μ < [y]

A sociologist found that in a random sample of 50 retired men, the average number of jobs they had during their lifetimes was 7.2. The population standard deviation is 2.1

Find the 99% confidence interval of the mean number of jobs. Do not round the z value, it should have two decimal places, example 2.34. Round the interval to one decimal place, example 3.2 < μ < 5.6

z value from the table for the formula:

Z-interval: [x] < μ < [y]

A random sample of 50 four-year-olds attending day care centers provided a yearly tuition average of $3987 and the population standard deviation of $630. Find the 90% confidence interval of the true mean. Round the interval to dollars without the dollar symbol, example 1234 < μ &λτ; 5678.

Z value from the table for the formula:

Z-interval: [x] < μ < [y]

The growing seasons for a random sample of 35 U.S. cities were recorded, yielding a sample mean of 190.7 days and the population standard deviation of 54.2 days. Estimate for all U.S. cities the true mean of the growing season with 95% confidence. Round the interval to the tenths place, example 5.4 < μ < 6.5.

Z value from the table for the formula:

Z-interval: [x] < μ < [y]

In a hospital study, the mean noise level in 171 randomly selected ward areas was 58.0 decibels, and the population standard deviation was 4.8. Find the 90% confidence interval of the true mean. Round the interval to one decimal place, example 4.5 < μ < 5.6.

Z value from the table for the formula

Z-interval: [x] < μ < [y]

A pizza shop wishes to find the 95% confidence interval of the true mean cost of a large plain pizza. How large would the sample be if she wishes to be accurate within $0.15? A previous study showed that the population standard deviation of the price was $0.26.

Round your answer up to the next whole number.

Z value from the chart for the formula:

Sample size: [x]

What is meant by degrees of freedom?

A meteorologist who sampled 13 randomly selected thunderstorms found that the average speed at which they traveled across a certain state was 1.7 miles per hour. The standard deviation of the sample was 1.7 mph. Find the 99% confidence interval of the mean. Do not round the t value from the table. Round the t-interval to one decimal place, example 1.2 < μ < 3.4

T value from the table for the formula:

T-interval: [x] < μ < [y]

A recent survey of 8 randomly selected social networking sites has a mean of 13.1 million visitors for a specific month. The standard deviation is 4.1 million. Find the 95% confidence interval of the true mean. Do not round the t value from the table. Round the interval to the tenths place, example 1.2 < μ < 3.4

T value from the table for the formula:

T-interval: [x] < μ < [y]

For a random sample of 24 operating rooms taken in a hospital study, the mean noise level was 41.6 decibels, and the standard deviation was 7.5. Find the 95% confidence interval of the true mean of the noise levels in the operating rooms. Do not round the t value from the table. Round the t interval to one decimal place, example 1.2 < μ &λτ; 3.4.

T value from the table for the formula:

T-interval: [x] < μ < [y]

What assumption must be made when computing confidence intervals for variances and standard deviations?

A study of generation related carbon monoxide deaths showed that a random sample of 6 recent years had a standard deviation of 4.1 deaths per year. Find the 90% confidence interval of the variance and standard deviation. Assume the variable is normally distributed.

Do not round the values from the table. Round the interval to the tenths place, example 1.2 < μ < 3.0.

χ² right: [a]

χ² left: [b]

Variance interval: [c] < σ² < [d]

Standard Deviation interval: [e] < σ < [f]

Find the 90% confidence interval for the variance and standard deviation of the ages of seniors at Oak Park College if a random sample of 24 students has a standard deviation of 2.3 years. Assume the variable is normally distributed. Use same rounding rules as the exercise above.

χ² right: [a]

χ² left: [b]

Variance Interval:  [c] < σ² < [d]

Standard Deviation Interval: [e] < σ < [f]