Conditional Probability

Here is the start of week 2. I went for my very first psychology lecture and it was so interesting, thanks to the prof who walked around and talk at the same time, without using the mike, and he can be louder than others who used the mike. I guess it was a good start to start the day off with an instrumental piece played by piano and cello, Taylor Swift's Love Story. However, because he was so interactive, I didn't quite dare to eat my breakfast in front of him. How I wish my core lecturers are as interesting as him, instead of just rattling notations and numbers off from the slides. =_="

Since we are doing conditional probability today, and I am teaching probability for tuition as well. Here's something I found from my worksheet and share it to you all:

Conditional Probability = False sense of security?
A stats professor plans to travel to a conference by plane. When he passes the security check, they discover a bomb in his carry-on-baggage. Of course, he is hauled off immediately for interrogation.
"I don't understand it!" the interrogating officer exclaims. "You're an accomplished professional, a caring family man, a pillar of your parish - and now you want to destroy that all by blowing up an airplane!"
"Sorry," the professor interrupts him. "I had never intended to blow up the plane."
"So, for what reason else did you try to bring a bomb on board?!"
"Let me explain. Statistics show that the probability of a bomb being on an airplane is 1/1000. That's quite high if you think about it - so high that I wouldn't have a peace on mind on a flight."
"And what does this have to do with you bringing a bomb on board of a plane?"
"You see , since the probability of one bomb being on my plane is 1/1000, that chance that there are two bombs is 1/10000000. If I already bring one, the chance of another bomb being around is actually 1/10000000, and I am much safer..."

HAHAHA!

Another one:

Are Mathematicians optimists?

A mathematician is flying non-stop from Edmonton to Frankfurt with AirTransat. The scheduled flying time is nine hours. Some time after taking off, the pilot announces that one engine had to be turned off due to mechanical failure: "Don't worry - we're safe. The only noticeable effect this will have for us is that our total flying time will be ten hours instead of nine."

A few hours into the flight, the pilot informs the passengers that another engine had to be turned off due to mechanical failure: "But don't worry - we're still safe. Only our flying time will go up to twelve hours."
Some time later, a third engine fails and has to be turned off. But the pilot reassures the passengers: "Don't worry - even with one engine, we're still perfectly safe. It just means that it will take sixteen hours total for this plane to arrive in Frankfurt."

The mathematician remarks to his fellow passengers: "If the last engine breaks down, too, then we'll be in the air for twenty-four hours altogether!"