How do you know 2 events are mutually excusive? Watch

Magenta96
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#1
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I know it means one event isn't affected by another so is it like they're independent? This question is confusing me where I have to show which 2 of 4 events are mutually exclusive from a table, it's question 5iii:

http://www.mei.org.uk/files/papers/s106ja_p3r112.pdf

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the bear
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mutually exclusive events are never independent

so one way of showing that events are not mutually exclusive is to show they are independent !

but the best way of determining mutual exclusivity is to show that p(A&B) is zero
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The Polymath
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Two events are mutually exclusive if the following is true:

If A occurs, then P(B) is unaffected. That is to say P(B|A) = P(B).

Edit: Oops, that's the definition of independence
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Cryogenic
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I think it's B & C. No athlete on the list competes in both the 200m and 110m hurdles, so they are mutually exclusive.
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Magenta96
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(Original post by the bear)
mutually exclusive events are never independent

so one way of showing that events are not mutually exclusive is to show they are independent !

but the best way of determining mutual exclusivity is to show that p(A&B) is zero
does it equal to zero because both events are mutually exclusive and so can't happen at the same time? Also, is the difference between independent events & mutually exclusive events that independent events can happen at the same time BUT aren't affected by each other and mutually exclusive events just can't happen together?

Thanks
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Magenta96
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(Original post by Cryogenic)
I think it's B & C. No athlete on the list competes in both the 200m and 110m hurdles, so they are mutually exclusive.
Yes it's B & C, thank you
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the bear
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(Original post by Magenta96)
does it equal to zero because both events are mutually exclusive and so can't happen at the same time? Also, is the difference between independent events & mutually exclusive events that independent events can happen at the same time BUT aren't affected by each other and mutually exclusive events just can't happen together?

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yes... it is like the probability of a coin landing on heads and tails...these events are mutually exclusive ( also exhaustive )

or the probability of a card being hearts and diamonds... these events are mutually exclusive ( but not exhaustive )
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Magenta96
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(Original post by the bear)
yes... it is like the probability of a coin landing on heads and tails...these events are mutually exclusive ( also exhaustive )

or the probability of a card being hearts and diamonds... these events are mutually exclusive ( but not exhaustive )
ah right yes that makes sense, thank you
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davros
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(Original post by The Polymath)
Two events are mutually exclusive if the following is true:

If A occurs, then P(B) is unaffected. That is to say P(B|A) = P(B).
That's the definition of independence!

A and B are mutually exclusive if they can't both happen together.

Examples:
I choose a number. A = the event that the number is even. B = the event that the number is odd.

I choose a playing card from a pack. A = the event that it is red. B = the event that it is black.
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The Polymath
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(Original post by davros)
That's the definition of independence!

A and B are mutually exclusive if they can't both happen together.

Examples:
I choose a number. A = the event that the number is even. B = the event that the number is odd.

I choose a playing card from a pack. A = the event that it is red. B = the event that it is black.
Oops haha. So mutual exclusivity is P(A&B)=0
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