Inaccuracy in Twitter timeline and search example

Created by: tangkangkai

In Calculate usage,

6,000 tweets per second 15 billion tweets delivered on fanout per month * (400 requests per second / 1 billion requests per month) 60 thousand tweets delivered on fanout per second 150 billion tweets delivered on fanout per month * (400 requests per second / 1 billion requests per month)

We probably want to use "15 billion tweets per month" instead.