Answer:
0.134 = 13.4% probability that a message is spam, given that it contains the word "text" (or "txt")
Step-by-step explanation:
We use the conditional probability formula to solve this question. It is
In which
P(B|A) is the probability of event B happening, given that A happened.
is the probability of both A and B happening.
P(A) is the probability of A happening.
In this question:
Event A: Contains the word "text", or "txt".
Event B: Spam message.
The word "text" (or "txt") is contained in of all messages, and in of all spam messages.
This means that
747 of the 5574 total messages () are identified as spam. The word "text" (or "txt") is contained in all of them. So
Then
0.134 = 13.4% probability that a message is spam, given that it contains the word "text" (or "txt")