Answer:
(0,5)
Step-by-step explanation:
I'm really not sure but I'm pretty positive that this is the answer if not than my bad
It’s less than 6 because 6x2:3 = 4
Solution :
Let A = Economics, B = Mathematics
n(A) = 311, n(B) = 243, 
a). So, 
= 311 + 243 - 135
= 419
b). n(A only) = 311 - 135
= 176
n(B only) = 243 - 135
= 108
Exactly one of these two courses

= 0.568
c). Neither economics nor mathematics


= 0.162