Problema Solution
Each face of a number cube is numbered 1,2,3,4,5,6. When the cube is tossed, each number is equally likely to appear face up. The number cube is tossed twice, and the numbers that land face up are recorded. What is the probability that the sum of the two recorded numbers is a prime number?
Answer provided by our tutors
The total number of outcomes is: 6*6 = 36
The number of outcomes where the sum of the two recorded numbers is prime is 14:
1 + 2 = 3
1 + 4 = 5
1 + 6 = 7
2 + 1 = 3
2 + 3 = 5
2 + 5 = 7
3 + 2 = 5
3 + 4 = 7
4 + 1 = 5
4 + 3 = 7
5 + 2 = 7
5 + 6 = 11
6 + 1 = 7
6 + 5 = 11
The probability that the sum of the two recorded numbers is a prime number is:
p = 14/36
p = 0.3889