Answer:
See below
Explanation:
<u>Check One-Sample T-Interval Conditions</u>
Random Sample? √
Sample Size ≥30? √
Independent? √
Population Standard Deviation Unknown? √
<u>One-Sample T-Interval Information</u>
- Formula -->
- Sample Mean -->
- Critical Value -->
(given
degrees of freedom at a 95% confidence level)
- Sample Size -->
- Sample Standard Deviation -->
<u>Problem 1</u>
The critical t-value, as mentioned previously, would be , making the 95% confidence interval equal to
This interval suggests that we are 95% confident that the true mean levels of lead in soil are between 381.5819 and 398.9181 parts per million (ppm), which satisfies the EPA's regulated maximum of 400 ppm.