Over winter vacation, Serena's class was assigned to read at least $200$ pages of a book. When school started again, she asked her teammates and the next closest team how many pages each of them had read. The answers were: $220, 312, 250, 483, 200, 0, 275$, and $495$.

1. Calculate the mean, median, and mode for the number of pages read.

   Hint (a):

   Creating a stem-and-leaf plot for this problem would be helpful.

2. If the person who did not do the assignment is not counted, how do the measures of central tendency change?

   Hint (b):

   Re-calculate the measures of central tendency leaving out the $0$. Which one changes the most?