Posted by **Shavela** on Saturday, April 21, 2012 at 2:43am.

An investigator wants to estimate caffeine consumption in high school students. How many students would be required to ensure that a 95% confidence interval estimate for the mean caffeine intake is within 15mg of the true mean? Assume the standard deviation in caffeine intake is 68mg. How many students would be required to estimate the proportion of students who consume coffee. Suppose we want the estimate to be within 5% of the true proportion with 95% confidence.

- Statistics -
**MathGuru**, Saturday, April 21, 2012 at 11:18am
Use formulas to find sample size.

For the first part:

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

...where n = sample size, z-value will be 1.96 using a z-table to represent the 95% confidence interval, sd = 68, E = 15, ^2 means squared, and * means to multiply.

For the second part:

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

... where n = sample size, z-value is 1.96, p = .5 (when no value is stated in the problem), q = 1 - p, ^2 means squared, * means to multiply, and E = .05 (for 5%).

Plug the values into the formulas and finish the calculations. Round your answers to the next highest whole number.

Hope this helps.

## Answer this Question

## Related Questions

- statistics - 2. An investigator wants to estimate caffeine consumption in high ...
- statistics - An investigator wants to estimate caffeine consumption in high ...
- statistics - Can someone guide me on how to solve this problem: A sample of 52 ...
- statistics - A random sample of 100 students from a high school was selected. If...
- elizabeth high school - . An admissions director wants to estimate the mean age ...
- AP Statistics - A school psychologist reports that the mean number of hours the ...
- Statistics - A sample of 53 night-school students' ages is obtained in order ...
- Statistics - An admissions director wants to estimate the mean age of all ...
- statistics - Randomly selected students participated in an experiment to test ...
- Elementary Statistics - 1) Construct a confidence interval of the population ...