# Math Help - proabability

1. ## proabability

The probability of an event and its complement equals one. True or false?

2. ## Re: proabability

Originally Posted by tukker0509
The probability of an event and its complement equals one. True or false?
$\mathcal{P}(E)+\mathcal{P}(E^c)=\mathcal{P}(E)+[1-\mathcal{P}(E)]=~?$

3. ## Re: proabability

Originally Posted by Plato
$\mathcal{P}(E)+\mathcal{P}(E^c)=\mathcal{P}(E)+[1-\mathcal{P}(E)]=~?$
What is that equation????!

4. ## Re: proabability

Originally Posted by jsweston828
What is that equation????!
Does the OP mean

$\mathcal{P}(E)+\mathcal{P}(E^c)$ OR $\mathcal{P}(E\cap E^c)~?$

5. ## Re: proabability

Im so confused! I just answered True!!

6. ## Re: proabability

Originally Posted by jsweston828
Im so confused! I just answered True!!
Well $\mathcal{P}(E)+\mathcal{P}(E^c)=1$ AND $\mathcal{P}(E\cap E^c)=0.$

7. ## Re: proabability

So would you say the answer is true or false!!

8. ## Re: proabability

Originally Posted by jsweston828
So would you say the answer is true or false!!
I have no idea. "The probability of an event and its complement equals one."
That is such a poorly constructed phrase as to be meaningless.
Look at reply #4. It could be either.

9. ## Re: proabability

ohhh I see! Im just going to hope its correct!