13. Megan writes down a list of five numbers. The mean of her first three numbers is -3 . The mean of her first four numbers is 4 . The mean of her first five numbers is -5 .
What is the difference between her fourth number and her fifth number?
A 66
B 55
C 44
D 33
E 22
13. A From the given information, the sum of Megan's first three numbers is -9 , the sum of her first four numbers is 16 , and the sum of her first five numbers is -25 .
Therefore the fourth number is $16-(-9)=25$, and the fifth number is $-25-16=-41$. The difference between them is $25-(-41)=66$.