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?

TheMathCoder
Apr 26, 2018

#1**+2 **

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

CPhill
Apr 26, 2018