E, F independent
P(exactly one)=2511
P(none)=252
To find: P(E), P(F)
Let p=P(E),q=P(F)
(1−p)(1−q)=252
p(1−q)+q(1−p)=2511
P(E∩F)=1−2511−252=2512
P(E∩F)=pq=2512
p+q−2pq=2511
p+q=2511+2⋅2512=2535=57
t2−57t+2512=0
t=257±51=54, 53
P(E)=54,P(F)=53 ⇒ option (1)