From participating cellphone users.1 in this collection, 747 of the 5574 total messages ( ) are identified as spam. of all spam messages, contain both the word "free" and the word "text" (or "txt"). for example, " you are selected to receive a free camera phone, txt to claim your prize." of all non-spam messages, contain both the word "free" and the word "text" (or "txt"). given that a message contains both the word "free" and the word "text" (or "txt"), what is the probability that it is spam? r