dice question

[Semidevil]

suppose 50 dices/dice/die/dies are tossed. approximate the probability that the sum of faces exceeds 170.

so first, I need to know the expected value of the sum of dices.....how do I do that? I can't find it or recall it in my book.

 

[icejunkie]

Easy!

 

[Semidevil]

still canot find...


bump^

 

[TwiceOver]

Its "Dice"

 

[Yossarian]

assuming that each die is labelled sequentially 1-6 or whatever, the average of each roll is (max+min)/2 = 3.5, so the average roll for 50 is 175.

 

[Platypus]

Use the CLT/normal distribution. Calculate the mean and the expected variance first.

 

[xXped0thugXx]

Originally posted by: Yossarian
assuming that each die is labelled sequentially 1-6 or whatever, the average of each roll is (max+min)/2 = 3.5, so the average roll for 50 is 175.

That is just the avg. If you wanted the possibilty that it would equal 170 you would have to assume that the dice were 1-6 as stated and that majority rolled were around a 3-4 area. If you assume that each Die had seperate quantities for example there were 20 5's 30 4's etc etc you can come up with a whole different amount of answers.

 

[Cerb]

Well, the average is (faces+1)/2
To get the probability of the sum exceeding 170, the first thing is to write a small program that does complete enumeration, and check the amount that are above 170 vs the amount below.

Unless this is for a math class, in which case you're probably screwed asking at AT.