Math Is Fun Forum

Hannibal lecter

Member

Registered: 2016-02-11

Posts: 392

please help me with that question as you can 9:05 bob bundy

Five balls (2 red , 1 blue , 1 green , 1 yellow )
are arranged in a circle, Find the probability that the red balls are not together

please help me with the answer, my exam is about 11 hours

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Wisdom is a tree which grows in the heart and fruits on the tongue

Bob

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Registered: 2010-06-20

Posts: 10,640

Re: please help me with that question as you can 9:05 bob bundy

In circular type questions the first red may be anywhere as all spaces are equal.  So now consider how to place the rest.

The space to the left of the red may be any of 3.  We'll assume we use one of these. The space to the right of the red may be any from the remaining two.  Now to place the rest.  Two ways to do that.So that's three x two x two = 12 ways.
Now to consider the total number of possibilities.

We've placed one red.  Left may be one from four and right one from three and once again two ways to place the rest.  That's 24 ways.

So P = 12/24

Bob

Good luck with the exam.

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Children are not defined by school ...........The Fonz
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