The Head Librarian at the Library of Congress Has Asked

Multiple Choice

The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books checked out each day. The assistant provides the following interval estimate:
From 740 to 920 books per day. If the head librarian knows that the population standard deviation is
150 books checked out per day, and she asked her assistant to use 25 days of data to construct the
Interval estimate, what confidence level can she attach to the interval estimate?

A) 99.7%
B) 99.0%
C) 98.0%
D) 95.4%