00:01
For this exercise, we consider rolling two fair dice, a green one and a red one.
00:07
And for part a, we are asked for the probability of getting a sum of seven.
00:17
Now, we can use the classic approach to probability here, which says that for some sample space, in this case, the sample space is all possible outcomes when rolling two dice.
00:30
For a given sample space, the probability of a specific event, in this case the sum being seven, is equal to the number of outcomes of the sample space that satisfy the event, divided by the total number of outcomes that are possible in the sample space.
00:50
This applies when all outcomes in the sample space are equally likely.
00:56
So when rolling two dice, this is a grid of 6 by 6.
01:00
So there are 36 outcomes in the sample space.
01:06
And the number of outcomes that result in a sum of 7 is the sum of these ones.
01:13
So we can see that there are six of them.
01:18
So this probability can be calculated as 6 over 36 or 1 over 6.
01:26
Now for b, we want the probability of getting a sum of 11.
01:33
So we use the same strategy as for part a.
01:44
And rolls that result in a sum of the 11 are these two...