# statistics

posted by .

A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 90% confident that her estimate is correct. If the standard deviation is 4.13, how large a sample is needed to get the desired information to be accurate within 0.68 decibels?

• statistics -

Formula:
n = [(z-value * sd)/E]^2
...where n = sample size, z-value will be found using a z-table for 90% confidence, sd = 4.13, E = 0.68, ^2 means squared, and * means to multiply.

Plug the values into the formula and finish the calculation. Round your answer to the next highest whole number.

## Similar Questions

1. ### statistics

A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 95% confident that her estimate is correct. If the standard deviation is 4.02, how large a sample is needed to get the desired …
2. ### statistics

A researcher is interested in estimating the average salary of teachers in a large urban school district. She wants to be 95% confident that her estimate is correct. If the standard deviation is \$1050, how large a sample is needed …
3. ### statistics

Suppose that a researcher is interested in estimating the mean systolic blood pressure, , of executives of major corporations. He plans to use the blood pressures of a random sample of executives of major corporations to estimate . …
4. ### Statistics

You are getting ready to take a sample from a large population, and need to determine the appropriate sample size. You are estimating sales at a large chain of department stores. A previous survey from the same population found a standard …
5. ### statistics

A researcher is interested in estimating the average salary of teachers in a large urban school district. She wants to be 95% confident that her estimate is correct. If the standard deviation is \$1050 (σ = 1050), how large of …
6. ### Statistics

A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 99% confident that the true mean is within 2 ounces of the sample mean?
7. ### statistics

confidence intervals: A researcher is interested in estimating the average salary of teachers in a large school district. She wants to be 95% confident that her estimate is correct. If the standard deviation is \$1050, how large a sample …
8. ### Basic Statistics

A researcher is interested in estimating the average salary of police officers in a large city. She wants to be 95% confident that her estimate is correct. If the standard deviation is \$1050,how large a sample is needed to get the …
9. ### math

A researcher is interested in estimating the average salary of Police officers in a large city. she want to be 95% confident that her estimate is correct. If the standard deviation is \$1050, how large a sample is needed to get the …
10. ### STATISTICS

Suppose that a researcher is interested in estimating the mean systolic blood pressure, , of executives of major corporations. He plans to use the blood pressures of a random sample of executives of major corporations to estimate . …

More Similar Questions