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.
Answer:
Maybe your answer is B
Answer:
The detailed answer to the question is explained in the attached file.
Explanation: