Posted by **Esmeralda** on Friday, December 9, 2011 at 10:34pm.

Three different numbers are chosen at random from the set {1,2,3,4,5}. The numbers are arranged in increasing order. What is the probability that the resulting sequence is an arithmetic sequence?

- Math -
**Reiny**, Friday, December 9, 2011 at 11:32pm
Since the order has to be increasing , the only possibilities are

1 2 3

2 3 4 , common difference of 1 for these three choices

3 4 5

1 3 5 , common difference of 2

(there are not enough numbers to have a common difference of 3)

The total number of triplets we can form are

5x4x3 = 60

Prob that our triplet forms an arithmetic sequence = 4/60 = 1/15

## Answer this Question

## Related Questions

Math - Three different numbers are chosen at random from the set {1,2,3,4,5}. ...

math - Three dierent numbers are chosen at random from the set f1; 2; 3; 4; 5g...

Algebra - True or False 1. – 5, – 5, – 5, – 5, – 5, … is an arithmetic sequence...

COLLEGE MATH PLEASE HELP - What do i do when order matters!!?!? The Sad State ...

Sequence and series - Do you know the difference between a sequence and a series...

math - Three numbers in an arithmetic sequence sum to six. If you add 1 to the ...

Math Concepts - What is the difference between an arithmetic sequence and a ...

math - what are the similarities and differences between an arithmetic sequence ...

Math - What numbers can be expressed as an alternating-sum of an increasing ...

Math - A sequence is called an arithmetic progression of the rst order if the di...