Can You Simplify Probability Calculations for Multiple Dice Rolls?

In summary, the conversation involves finding the probability of the sum of three rolled die being less than or equal to 9. The solution suggested is to consider the total as the sum of two dice and the third, utilizing the known probabilities of rolling two dice. An example is given to illustrate this approach.
  • #1
ArcanaNoir
779
4

Homework Statement



"Find the probability of the sum of three rolled die being less than or equal to 9."

Given problems like this, my question is: is there some way to find the answer besides writing out all 216 combinations and then counting the ones that equal 9? I feel like there is, but I'm just being blind.
 
Physics news on Phys.org
  • #2
You could consider the total as being the sum of two dice and the third. Presumably, you know the probabilities involved with rolling two dice.

For example, the probability of rolling a 3 would be P(first two=2)xP(last die=1) = (1/36)(1/6) = 1/216.
 
  • #3
Ah, that looks good. Thanks!
 

1. What is counting for probability?

Counting for probability is a method used to determine the likelihood of a particular event occurring. It involves counting the number of possible outcomes in a given sample space and using this information to calculate the probability of a specific outcome.

2. How is counting used in probability?

Counting is used in probability to determine the number of possible outcomes in a given situation. This information is then used to calculate the probability of a specific outcome occurring.

3. What is the difference between permutations and combinations?

Permutations and combinations are both methods used to count the number of possible outcomes in a situation. However, permutations take into account the order of the outcomes, while combinations do not. Permutations are used when order matters, while combinations are used when order does not matter.

4. How do you calculate the number of permutations or combinations?

The number of permutations or combinations can be calculated using specific formulas. For permutations, the formula is nPr = n! / (n-r)!, where n is the total number of items and r is the number of items being selected. For combinations, the formula is nCr = n! / (r!(n-r)!), where n is the total number of items and r is the number of items being selected.

5. Can counting be used for more complex probability problems?

Yes, counting can be used for more complex probability problems. It can be combined with other mathematical concepts, such as combinations, to solve problems involving multiple events. In these cases, the sample space may be larger and more calculations may be necessary to determine the probability of a specific outcome.

Similar threads

  • Precalculus Mathematics Homework Help
Replies
3
Views
1K
  • Precalculus Mathematics Homework Help
Replies
1
Views
1K
  • Set Theory, Logic, Probability, Statistics
Replies
6
Views
1K
  • Precalculus Mathematics Homework Help
Replies
11
Views
2K
  • Precalculus Mathematics Homework Help
Replies
8
Views
2K
  • Precalculus Mathematics Homework Help
Replies
14
Views
3K
  • Precalculus Mathematics Homework Help
Replies
2
Views
2K
  • Precalculus Mathematics Homework Help
Replies
22
Views
2K
  • Precalculus Mathematics Homework Help
Replies
4
Views
1K
  • Precalculus Mathematics Homework Help
Replies
9
Views
1K
Back
Top