Hi everybody, just a heads up there is a pre-test tomorrow so be prepared.

Any who today in class we learned two new topics. These topics are called Mutually exclusive and Non Mutually exclusive events. The way something can be mutually exclusive is if it is impossible for them to occur together. Basically like saying you can't be the age 31 and at the same time be 16, there is just no way. Or like saying can you roll a die and get both a positive and negative number at the same time.

Examples

Drawing one card either, a black ace or a red two

When randomly selecting two animals from a barn either a, cat or dog

Randomly selecting a person either a, girl or a boy

Now non mutually exclusive events are the exact opposites when things can happen together, like either drawing from a deck of cards a king or a spade. You can actually draw a king of spades.

Examples

Selecting a person for your basketball team who is either, fast or tall

Sleeping with either a, long pillow or comfy pillow

Rolling a two dice and either getting a sum of an odd number or a double

Although you may just think of this as the exact opposite to mutually exclusive events there is more thinking involved. Mutually exclusive event formula is (A) n (B) = zero set, done. For non mutually exclusive events there is a big formula you have to follow.

Using Mr.K's example I will explain

You wish to draw either a king or a spade from a single deck
A represents kings
B represents spades
Now remember one card is both keep this in mind

So the formula looks like this P ( A U B ) = P(A) + P(B) - P(AnB)
Plug in the numbers and you it looks like
P ( A U B ) = 4/52 + 13/52 - 1/52
= 1/16

WHOA, why did we subtract the 1/52 people may ask, reason being because the card gets counted so we want to subtracted it so that it doesn't get counted twice.

So that is what we learned in class what I recommend doing is try to make up your own mutually and non mutually exclusive events and practise further with the formula. Now the next scribe I choose is IRIS......