I have end of semester exams coming up and my tutor has posted an example exam. One of the example questions is as follows:

A study of 113 dead pelicans found that 47 had foreign objects in their gut. An approximate 95% confidence interval for the population proportion of pelicans with foreign objects in their gut is:

(A) 0.416 +- 0.0464

(B) 0.416 +- 0.139

(C) 0.416 +- 0.0909

(D) 0.416 +- 0.0927

(E) 0.416 +- 0.119

Now we know the answer is (D) however nobody in my study group knows how to get it. Even my private tutor couldn't help on this one. Any help and assistance would be appreciated.