Theoretical Probability: 512, or about 42 % Number of Days: About 3 days per week
Practice makes perfect
We want to calculate the theoretical probability that Myriah will have to wash the dishes. We know that Myriah rolls two dice each day, and she has to wash the dishes if the sum of the two rolled numbers is at most 6. Let's write down all of the possible sums that we can get when rolling two dice. We will highlight all values that are 6 or less.
1
2
3
4
5
6
1
2
3
4
5
6
7
2
3
4
5
6
7
8
3
4
5
6
7
8
9
4
5
6
7
8
9
10
5
6
7
8
9
10
11
6
7
8
9
10
11
12
Remember that theoretical probability is the quotient of the number of favorable outcomes and the total number of possible outcomes. We can see that there are 15 favorable outcomes out of 36 possible outcomes. Let's calculate the probability!
P(Myriah washing dishes)=15/36=5/12
The theoretical probability that Myriah will have to wash the dishes is 512, or about 42 %. Finally, let's calculate the number of days Myriah can expect to wash the dishes per week. To do so, we can multiply the probability by the numbers of days in the week.
5/12*7≈ 3
Myriah can expect to wash the dishes about 3 days a week.
