According to the given confidence interval, we have that:
a) It means that we are 95% sure that the population mean amount of sleep for all students at the high school is between 5.39 and 7.81 hours.
b) The point estimate is of 6.6 hours, with a margin of error of 1.21 hours.
c) Since the entire confidence interval is below 8 hours, it is found that there is enough evidence to conclude that the students at this high school are not getting the recommended amount of sleep.
<h3>What is the interpretation of a x% confidence interval?</h3>
It means that we are x% confident that the population parameter(mean/proportion/standard deviation) is between a and b.
Additionally, from an interval (a,b), we have that:
- The point estimate is
.
- The margin of error is of
.
Item a:
It means that we are 95% sure that the population mean amount of sleep for all students at the high school is between 5.39 and 7.81 hours.
Item b:
The <em>point estimate</em> is:

The <em>margin of error</em> is:

The point estimate is of 6.6 hours, with a margin of error of 1.21 hours.
Item c:
Since the entire confidence interval is below 8 hours, it is found that there is enough evidence to conclude that the students at this high school are not getting the recommended amount of sleep.
More can be learned about confidence intervals at brainly.com/question/25779324