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Mathematics 10 Online
OpenStudy (dannyo19):

Three fair dice are tossed. What is the probabiligy that the three numbers turned up can be arranged to form an arithmetic sequence?

OpenStudy (dannyo19):

I have an answer but I'm looking for someone who can explain how to do it

OpenStudy (loser66):

@Zarkon I am waiting for your explanation. Please, explain us.

OpenStudy (zarkon):

list out some possible arithmetic sequences...in monotone order...there aren't that many. then permute them to get the total number

OpenStudy (loser66):

Do we have to raise to the power of 3 ? I meant let say 1-2-3 as one possibility, and 1 for dice 1, 2 for dice 2, and 3 for dice 3. The order can apply for 1 for dice 2, 2 for dice 1 and 3 for dice 3. So that we need to raise the possibility to 3, right?

OpenStudy (zarkon):

1,2,3 1,3,2 2,1,3 2,3,1 3,1,2 3,2,1 3! possibilities for 1,2,3

OpenStudy (loser66):

Got you. Thanks for explanation.

OpenStudy (dannyo19):

132 is an arithmetic sequence?

OpenStudy (dannyo19):

No, I think one sequence can either increase or it can decrease. It can't do both.

OpenStudy (zarkon):

" CAN be arranged to form an arithmetic sequence"

OpenStudy (zarkon):

132 can be arranged as 123

OpenStudy (dannyo19):

123, 135, 234, 246, 345, 456 , so are you saying there would be 36?

OpenStudy (zarkon):

there are more

OpenStudy (dannyo19):

not 3 factorial for each of those groups?

OpenStudy (zarkon):

111,222,...,666 are arithmetic (common difference of 0)

OpenStudy (dannyo19):

Right so 42?

OpenStudy (zarkon):

yes

OpenStudy (dannyo19):

The way to find the total number of different combos though?

OpenStudy (zarkon):

you just did

OpenStudy (dannyo19):

No those were possible arithmetic sequences. I need a probability, so 42/x

OpenStudy (zarkon):

6 possibilities for each die \(6^3=216\) total

OpenStudy (dannyo19):

then there's the fact that 116 is the same as 161 and 611

OpenStudy (zarkon):

and...

OpenStudy (zarkon):

out of the 216 possible ways to roll the dice we found 42 that can be arranged into an arithmetic sequence

OpenStudy (dannyo19):

Okay, thank you.

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