Probability: What do "and" and "or" mean?

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hatesmath2011
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Probability: What do "and" and "or" mean?

Postby hatesmath2011 » Sun Apr 17, 2011 10:17 pm

Hello :wave: I need help on probabilty...
First things first: What do "and" and "or" mean? I am confused if...and=multiplication | or=adding the two probabilities together.
Does mutually exclusive mean that the two events can't happen at the same time?
And I don't know what are overlapping/ independent/ dependent events....

A problem from my math packet:
2.There are two bags of coins. Each bag holds 1 nickel, 1 dime and 1 quarter. Choose one coin @ random from each bag. Find the probability of getting the following.
a) P(both are nickels)
b) P(exactly one nickel)
c) P(no nickels)
d) P(at least one dime)
e) P(all dimes)
f) P(at most one quarter)
g) P(both are same coins)
h) P(both are different coins)

Okay...so I got a,b, and c, but my friend did it, so I don't understand. a= 1/9, b=4/9, c=4/9. <--- Is that correct? If yes can you please explain it to me? :confused:

Thanks! :D

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maggiemagnet
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Re: Probability: What do "and" and "or" mean?

Postby maggiemagnet » Mon Apr 18, 2011 1:27 pm

hatesmath2011 wrote:What do "and" and "or" mean? I am confused if...and=multiplication | or=adding the two probabilities together.

Maybe if you could provide a couple examples of what you mean...?

hatesmath2011 wrote:Does mutually exclusive mean that the two events can't happen at the same time?

Yes.

hatesmath2011 wrote:And I don't know what are overlapping/ independent/ dependent events....

Your book should have the definitions that you should use.

hatesmath2011 wrote:A problem from my math packet:
2.There are two bags of coins. Each bag holds 1 nickel, 1 dime and 1 quarter. Choose one coin @ random from each bag. Find the probability of getting the following.
a) P(both are nickels)
b) P(exactly one nickel)
c) P(no nickels)
d) P(at least one dime)
e) P(all dimes)
f) P(at most one quarter)
g) P(both are same coins)
h) P(both are different coins)

Okay...so I got a,b, and c, but my friend did it, so I don't understand.

What did you get? What was your reasoning?

:clap:

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Martingale
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Re: Probability: What do "and" and "or" mean?

Postby Martingale » Mon Apr 18, 2011 1:56 pm

hatesmath2011 wrote:Hello :wave: I need help on probabilty...
First things first: What do "and" and "or" mean? I am confused if...and=multiplication | or=adding the two probabilities together.


and independent if and only if


if and are mutually exclusive then


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