# roll of the die

• Jul 18th 2006, 08:17 PM
zoso
roll of the die
Even number = that number is added to your score

Odd number = that number subtracted from your score

What is the expected value of a single roll of the die, and how is it calculated?
• Jul 18th 2006, 08:25 PM
Quick
Quote:

Originally Posted by zoso
Even number = that number is added to your score

Odd number = that number subtracted from your score

What is the expected value of a single roll of the die, and how is it calculated?

Tell me, what is the average score of all the possible outcomes?

I'll show you...

note: $\displaystyle s_1$ is the amount of points you'll get when you roll a 1

average is:

$\displaystyle \frac{s_1+s_2+s_3+s_4+s_5+s_6}{6}=\frac{\neg1+2-3+4-5+6}{6}=\frac{3}{6}=\boxed{\frac{1}{2}}$

and that is the expected outcome for a single roll of the die. Yes I know it's impossible to get that number with a die, but that's the best math has to offer.
• Jul 18th 2006, 08:26 PM
malaygoel
Quote:

Originally Posted by zoso
Even number = that number is added to your score

Odd number = that number subtracted from your score

What is the expected value of a single roll of the die, and how is it calculated?

Expected value of a single roll of dice is 3.5

Malay
• Jul 18th 2006, 08:31 PM
Quick
Quote:

Originally Posted by malaygoel
Expected value of a single roll of dice is 3.5

Malay

oooooh, conflict. How would you find 3.5 as an answer if that is higher than the expected outcome if all numbers counted as positive?
• Jul 18th 2006, 08:40 PM
malaygoel
Quote:

Originally Posted by Quick
oooooh, conflict. How would you find 3.5 as an answer if that is higher than the expected outcome if all numbers counted as positive?

There are six numbers and the probability of any one of them is 1/6.
Hence expected value=$\displaystyle \frac{1}{6}.1 + \frac{1}{6}.2 + \frac{1}{6}.3 + \frac{1}{6}.4 + \frac{1}{6}.5 + \frac{1}{6}.6$

Malay
• Jul 18th 2006, 08:41 PM
zoso
Quote:

Originally Posted by Quick
Tell me, what is the average score of all the possible outcomes?

I'll show you...

note: $\displaystyle s_1$ is the amount of points you'll get when you roll a 1

average is:

$\displaystyle \frac{s_1+s_2+s_3+s_4+s_5+s_6}{6}=\frac{\neg1+2-3+4-5+6}{6}=\frac{3}{6}=\boxed{\frac{1}{2}}$

and that is the expected outcome for a single roll of the die. Yes I know it's impossible to get that number with a die, but that's the best math has to offer.

blatantly simple, I really need to think more
• Jul 18th 2006, 08:43 PM
Quick
Quote:

Originally Posted by malaygoel
There are six numbers and the probability of any one of them is 1/6.
Hence expected value=$\displaystyle \frac{1}{6}.1 + \frac{1}{6}.2 + \frac{1}{6}.3 + \frac{1}{6}.4 + \frac{1}{6}.5 + \frac{1}{6}.6$

Malay

You didn't read the entire question, if the number is odd, than it's subtracted from the score.
• Jul 18th 2006, 08:46 PM
malaygoel
Quote:

Originally Posted by Quick
You didn't read the entire question, if the number is odd, than it's subtracted from the score.

Sorry
Yes, if it is to be subtracted. then the answer is 0.5.

Malay
• Jul 18th 2006, 08:48 PM
malaygoel
Quote:

Originally Posted by zoso
blatantly simple, I really need to think more

You are correct here.
Extend it.
Try for double throw of dice.

Malay