The number of students who do not check their e-mail accounts on a regular basis is 121-88=33.
And the proportion for that is 33/121 = 0.27 which is a percentage of 27%
Now let's write the information we have :
sample size ---> n=121
and we have a proportion of 0.27 as we calculated before, so:
Now let's replace the information we already have in the equation provided:
Finally the confidence interval for the percentage of students at the college who do not check their email account on a regular basis is 17.6% < p < 36.4%
The lower endpoint is: 17.6%
The upper endpoint is: 36.4%