Answer:
They can either decrease the confidence level or increase the sample size, that is, survey more students.
Step-by-step explanation:
The width of a confidence interval is given by:
In which z is the critical value correponding to the confidence level(higher confidence level, higher z is), is the standard deviation of the population and n is the size of the sample.
The students realize that this interval contains a large margin of error. What can they do to make a narrower interval?
Looking at the formula for M, they can either decrease the confidence level or increase the sample size, that is, survey more students.