Probability question....

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countrymum
Posts: 686
Joined: Tue Mar 08, 2011 10:16 am

Probability question....

Post by countrymum »

Would really like to understand this one....

For which of these can you work out the probability exactly?

A) It will rain tomorrow when class B go on a school trip.
B) Mr. Wood will pass his driving test
C) Stuart will miss the 8.30 am bus to school
D) Emily will throw heads when she tosses a coin
E) Amy will come third in a swimming competition

?????
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Probability question....

Post by Guest55 »

D is the only one where the outcomes are equally likely.

Two outomes Head or tail - probability of a Head is 1/2.
countrymum
Posts: 686
Joined: Tue Mar 08, 2011 10:16 am

Re: Probability question....

Post by countrymum »

Guest55 wrote:D is the only one where the outcomes are equally likely.

Two outomes Head or tail - probability of a Head is 1/2.
Thanks Guest55
What about passing/failing driving test isn't that 1/2 ( pass or fail )
Is this a straight forward one, have really struggled on it....
Manana
Posts: 710
Joined: Wed Mar 09, 2011 3:22 pm

Re: Probability question....

Post by Manana »

countrymum wrote:
B) Mr. Wood will pass his driving test

D) Emily will throw heads when she tosses a coin

Both these are 50/50
hermanmunster
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Joined: Fri Sep 15, 2006 9:51 am
Location: The Seaside

Re: Probability question....

Post by hermanmunster »

I think that for the probability to be calculated you have to know that each outcome is equally likely . heads or tails is equally likely but passing or failing a test may not be equally likely
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Probability question....

Post by Guest55 »

Passing and failing a driving test are not equally likely - I think it varies from test centre to test centre and a driver could be appalling.

Theoretical probability only applies where 'skill' is not part of the picture - spinning a coin, throwing a die, etc.

Playing football depends on the teams playing - the weather depends on the time of year and the country.
dottie1974
Posts: 192
Joined: Thu Nov 12, 2009 2:36 pm
Location: East Kent

Re: Probability question....

Post by dottie1974 »

Manana wrote:
countrymum wrote:
B) Mr. Wood will pass his driving test

D) Emily will throw heads when she tosses a coin

Both these are 50/50
I guess someone is only likely to take their driving test if they think the odds are they are likely to pass - a coin toss has no element of skill (in that practice can have any outcome on the result you are likely to get)
countrymum
Posts: 686
Joined: Tue Mar 08, 2011 10:16 am

Re: Probability question....

Post by countrymum »

Guest55 wrote:Passing and failing a driving test are not equally likely - I think it varies from test centre to test centre and a driver could be appalling.

Theoretical probability only applies where 'skill' is not part of the picture - spinning a coin, throwing a die, etc.

Playing football depends on the teams playing - the weather depends on the time of year and the country.
Thanks everyone and guest55, thanks so much for that. It has all clicked and I get it now! Kind of thinking out of the box and taking many outside influences into account ( like for eg the weatherman mayhave got it wrong or like you say he may a rubbish driver etc etc )

Yes the answer is indeed D! If I get stuck again can I come back :lol:
You are all masters of maths :D
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Probability question....

Post by Guest55 »

I should hope so as I spend my life teaching it!
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