Maths S1

When two events are mutually exclusive, are they automatically independent or dependent? I am so confused, please help...!

Reply 1

tripplea

Original post by Meraki1

When two events are mutually exclusive, are they automatically independent or dependent? I am so confused, please help...!

My understanding is that when events have no outcomes in common, they are mutually exclusive - they don't intersect.

When an event has no effect on the another they are independent - but they can still intersect.

Reply 2

RDKGames

Study Forum Helper

Original post by Meraki1

When two events are mutually exclusive, are they automatically independent or dependent? I am so confused, please help...!

Independence does not depend on mutual exclusivity.

Mutually exclusive: Two or more events cannot happen at the same time.

Independent: The probability of one or more events happening does not depend on some other.

For example, consider yourself in a scenario where you go to buy snacks for a sick rave from either Tesco or Sainsburys. The probability that you buy cookies if greater IF you buy milk.

The mutually exclusive case here is that you go to either Tesco or Sainsburys, you cannot go to both. The independence case here is that if you are more likely to buy cookies if you buy milk, so the probability that you buy cookies GIVEN that you buy milk, is different to the probability that you do not buy milk and still buy cookies. A slight twist on the scenario can be that you are completely indifferent to your snack combos so the probability that you buy cookies is left unchanged whether or not you buy the milk.

Get it?

(edited 6 years ago)

Reply 3

tripplea

http://www.examsolutions.net/tutorials/probability-laws/?level=A-Level&board=Edexcel&module=S1&topic=11137