Two number cubes are rolled. What is the probability that the sum of the numbers rolled is either 4 or 8?
A. \( \frac{1}{9} \)
B. \( \frac{2}{9} \)
C. \( \frac{5}{18} \)
D. \( \frac{5}{432} \)
Answer (2)
There are 6 * 6 = 36 possible dice combinations.
For the sum to be a 4, there are 3 possible rolls: 1,3 3,1 2,2
So the probability the sum is 4 is 3 * 1/36 = 3/36
For the sum to be an 8, there are 7 possible rolls: 2,6 6,2 3,5 5,3 4,4
So the probability the sum is 8 is 7*1/36 = 7/36
So the probability the sum is 8 or 4 is:
3/36 + 7/36 = 10/36 = 5/18 = 0.278 (3 s.f.)
The probability that the sum of the numbers rolled on two cubes is either 4 or 8 is 9 2 . This is calculated by finding the total number of favorable outcomes for each sum and dividing by the total possible outcomes. The answer choice is B. 9 2 .
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