Question

Andrew arranged the number 1, 2, 3, ...11, 12 into six pairs so that the sum ofany two numbers in a pair is prime and no two of these primes are equal. find the primes and the pairs

Answer 1

I had to solve this by "trial and error" and finally came up with this. There many be other solutions.
1 + 4 = 5
2 + 5 = 7
3 + 8 = 11
6 + 7 = 13

9 + 10 = 19
11 + 12 = 23

Other prime-number-sum combinations possible would have been 3 and 17, but by forming them I had to use numbers twice or get duplicate sums.

Answer 2

(5,8);(3,2);(1,6);(9,10);(4,7);(11,12).

5+8=13
3+2=5
1+6=7
9+10=19
4+7=11
11+12=23

Hope that helps!!!!! :)

Answer 3

1+2=3
3+4=7
5+8=11
6+7=13
9+10=19
11+12+23