Posted by **Tom** on Saturday, March 13, 2010 at 9:26pm.

Calculate the following:

a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10.

b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence.

- Statistics -
**MathGuru**, Monday, March 15, 2010 at 6:51pm
Formula for a):

n = [(z-value * sd)/E]^2

...where n = sample size, z-value will be found using a z-table to represent the 90% confidence interval, sd = 10, E = 1, ^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.

For b) Use a confidence interval formula:

CI90 = mean + or - z-value (sd/√n)

I'll let you take it from here.

- Statistics -
**Anonymous**, Wednesday, December 5, 2012 at 1:29am
10

## Answer this Question

## Related Questions

- statistics - what are the mean and standard deviation of a sampling distribution...
- statistics - An IQ is designed so that the mean is 100 and the standard ...
- Statistics - An IQ test is designed so that the mean is 100 and the standard ...
- statistics - Use the given information to find the minimum sample size required ...
- Statistics - An admissions director wants to estimate the mean age of all ...
- statistics - A statistics practitioner would like to estimate a population mean ...
- statistics - Use the given information to find the minimum sample size required ...
- statistics - A population has a mean of 300 and a standard deviation of 50. ...
- math statistics - The average price of a gallon of unleaded regular gasoline was...
- math statistics - please help me I've waited for hours The average price of a ...