Using the t-distribution, as we have the standard deviation for the sample, it is found that the 90% confidence interval is (246.6, 282.8).
<h3>What is a t-distribution confidence interval?</h3>
The confidence interval is:

In which:
is the sample mean.
- s is the standard deviation for the sample.
The critical value, using a t-distribution calculator, for a two-tailed <u>90% confidence interval</u>, with 16 - 1 = 15 df, is t = 1.7531.
Researching the problem on the internet, the standard deviation was of 42.1 mg/dL, hence the parameters are as follows:

Thus, the bounds of the interval are given by:


The 90% confidence interval is (246.6, 282.8).
More can be learned about the t-distribution at brainly.com/question/16162795