die number : 1 2 3 4 5 6
probability of getting even number : 3/6
because the number 2,4,6 are even number
the number 3 is 'how many even number?'
while 6 is the total number in throwing a die
probability of getting prime number : 2/6
because the number 3,5 are only prime number
the number 2 is 'how many prime number?'
while 6 is the total number in throwing a die
the question ask : getting even OR prime number
this means that we have to add the probability of even and prime number
3/6 + 2/6 = 5/6 (answer)
