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## wannabegurl 2 years ago Can somebody explian to me dependent and independent probability

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1. wio

Independent events in probability is when two events do not affect each others outcome. For example if you flip a coin twice, the event that the first flip is heads is independent of the event that the second flip is heads.

2. wio

However if you have an event where both flips are heads, then the event that the first flip is heads affects the outcome of this event. You know it is more likely to happen then before the first flip. Thus the events are dependent on each other.

3. wio

The significance of this is that if two events are independent, then the chance of then both happening is $\Pr(AB) = \Pr(A) \times \Pr(B)$

4. wannabegurl

@wio so if I had a bag with a square ,circle,two triangles what. Would be P(T,circle) ?

5. wio

What do you mean P (T, circle)? what are the events?

6. wannabegurl

@wio sorry and a penny so tails would be T in P(T,circle)

7. wio

What is the even that is happening?

8. wio

a penny so tails is not an event.

9. jim_thompson5910

it sounds like P(T,circle) = "probability of flipping a penny to land on tails AND picking a circle out of the bag"

10. wio

@wannabegurl is he right?

11. wannabegurl

Yes @wio he is right thanks @jim_thompson5910

12. wio

Then use the formula I wrote, since the flip is independent of the draw. $\Pr(T,\circ)=\Pr(T)\times \Pr(\circ)$

13. wannabegurl

Ok @wio if you say soo

14. jim_thompson5910

You could draw out a table to help you find the probability |dw:1361673237553:dw|

15. jim_thompson5910

Each cell would get the respective header from each row and column for example, this cell marked with an X |dw:1361673403499:dw| would have "H, Square" and this is the outcome where you flip a heads and pull out a square so you would enter that into the upper right cell to get |dw:1361673459247:dw|