Question 970991
Make a table with 1000

 =========R      =====                   D ;;;;;            Total

Voted         385      =====               195    ;;;;             580               



Non-vote   315      ====                105    ;;;;             420

total          700      ====                300      ;;;;           1000

Prob (Republican)=385/580=0.66


Prob (contributor)= 0.37+0.43-0.15 (double count)=0.65
Probability non-contributor is 0.35