Conditional Probability

Some students complain that they often read a question and cannot figure if there is a conditional probability present. So lets hope the following explanation will aid them to better understand it. Lets state the formula first.

P(A|B) = \frac{P(A \cap B)}{P(B)}

Probability is always Counter Intuitive.

How does that work? I will first tell students that B is usually the event that had occurred, it is a prior information to A occurring. Other words, P(A|B) is really the probability that A will happen, knowing B had occurred. Consider A to be the event you go to the beach and B is the event the newscaster announce thunderstorm. After B occurred, the chances (probability) of you doing A, will definitely decrease.

So keywords to look out for in A-levels, “if, given, knowing”.

Leave a Comment

seven + 20 =

Contact Us

CONTACT US We would love to hear from you. Contact us, or simply hit our personal page for more contact information

Not readable? Change text. captcha txt

Start typing and press Enter to search