Paul and Jesse each choose a number at random from the first six primes. What is the probability that the sum of the numbers they choose is even?
First 6 primes =
2, 3, 5, 7, 11, 13
Notice that each can choose any one of six numbers....so...the total number of possibilities is 6 * 6 = 36
But the only odd sums occur when one of the chooses a 2 and the other chooses an odd prime....
So for (Paul, Jessie)....these will occur as ( 2, odd) or ( odd, 2)
And there are 10 total sets where an odd sum occurs...so....the probability of an even sum is :
26/36 = 13/18