A bag contains the numbers 1 through 20 inclusive. If three are selected at random and placed in order from smallest to largest, find the probability that the arrangement is of three consecutive integers.

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- Nov 1st 2006, 05:17 AMpunmasterProbability
A bag contains the numbers 1 through 20 inclusive. If three are selected at random and placed in order from smallest to largest, find the probability that the arrangement is of three consecutive integers.

- Nov 1st 2006, 01:25 PMearboth
- Nov 1st 2006, 01:42 PMThePerfectHacker
Here is another way.

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Probability is favorable to possible.

What is favorable?

{1,2,3} All premutations of this set = 6

{2,3,4} All premutations of this set = 6

.....

{18,19,20} All premutations of this set = 6

In total we have,

18 Sets

Thus,

The possible outcomes is the number of ways of selecting 3 out of twenty.

Which is,

Thus,

- Nov 1st 2006, 02:04 PMPlato
- Nov 1st 2006, 02:07 PMThePerfectHacker