00:01
For this exercise, we consider rolling a six -sided die twice, and we have defined an event a as the first die being odd, and the second being a four, a five, or a six.
00:15
And for part a, we are asked to find the probability of event a.
00:20
And here we can use the classic approach to probability, which says that for a sample space that has equally likely outcomes, so in this case, the sample space is the 36 possible dice rolls.
00:34
Then the probability of a given event is equal to the number of outcomes resulting in that event divided by the total possible number of outcomes in the sample space.
00:46
So this is the number of outcomes that satisfy event a, divided by the number of outcomes in the sample space.
00:56
So let's identify all dice rolls that satisfy event a.
01:01
The first die has to be odd, and the second is 4 or 5 or 6.
01:05
So it's these outcomes highlighted in yellow.
01:12
And there is a total of nine of them.
01:15
The total number of possible dice rolls when rolling a die twice is 36.
01:22
And so this comes out to one quarter.
01:27
And then for b, we want to find the probability that the sum is 10.
01:39
There are three outcomes for which the sum is 10.
01:43
These three here.
01:53
So we have 3 over 36.
02:01
This comes out to 0 .0833 approximately...