Paul and Jesse each choose a number at random from the first seven primes. What is the probability that the sum of the numbers they choose is even?
First seven primes
2, 3 ,5 ,7 ,11, 13, 17
2 3 5 7 11 13 17
2 5 7 9 13 15 19
3 5
5 7
7 9
11 13
13 15
17 19
There are 49 possible outcomes
14 are odd
So
P (even sum) = ( 49 - 14 ) / 49 = 35 / 49 = 5 / 7
