Tom and Jim decided to play the following game for points. A single die is rolled. If it shows a non-prime number, Tom receives points equal to two times the number of dots showing. If it shows a prime number, Tom loses points equal to three times the number of dots showing. What is the expected value of the game?
because, a die has 6 faces: 1,2,3,4,5,6
prime numbers: 2,3,5
non-prime numbers: 1,4,6
probability of getting a prime number q = 3/6 = ...
Expected value is calculated based on probabilities.