Question

Two 6-sided dice are rolled. what is the probability that the sum of the two numbers on the dice will be greater than 9?

Answer 1

What combination of numbers are needed in order to get a sum of 9?
It can be:
• First die is 6 , second die is 3
• First die is 3 , second die is 6
• First die is 4 , second die is 5
• First die is 5 , second die is 4

How many possible combinations are made? Yep, 4 possible combinations.

Recall the formula for probability

`Probability = (Number of desired outcomes)/(Number of all possible outcomes)`

There are 4 desired number of outcomes.
How about the total possible outcomes?
• How many numbers are possible to appear when the first die is rolled?
Answer: 6
• What about the second die?
Answer: Also 6
• Therefore, total possible outcomes = 6 * 6 = 36 outcomes

You can now solve for the probability.


`Probability = (4)/(36) = (1)/(9)` or approximately 11.11%