A librarian was trying to figure out the number of books in the nonfiction section. The values below represent the numbers of books on each shelf of a corner bookcase. 27, 15, 23, 15, 22, 18, 16, 14, 23, 25, 13, 29

Which measure of central tendency should the librarian use?
the mean
the median
either the mean or median since they are the same
neither the mean nor median because there is too much variability