The set of events that the sum of the numbers showing face up is at least 9 is E = {36, 45, 46, 54, 55, 56, 63, 64, 65, 66} and the probability is 5/18.
In the roster form, the elements (or members) of a set are listed in a row between curly brackets. For the event that the sum of the numbers showing face up is at least 9 and is written as a set, look at the sum of values of blue and gray dies that has values greater than equal to 9.
Here, the total outcome S = 36
By doing that, we get,
E = {36, 45, 46, 54, 55, 56, 63, 64, 65, 66} = 10
Then, the probability of getting a sum of at least 9 is calculated as,
[tex]\begin{aligned}P(X\geq 9)&=\frac{\text{Number of favorable outcomes}}{\text{total number of outcomes}}\\&=\frac{n}{S}\\&=\frac{10}{36}\\&=\frac{5}{18}\;\text{or}\;0.28\end{aligned}[/tex]
The answer is 5/18.
To know more about roster notation:
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