In a race where 16 cars are running, the chance that car X will win is 1/4, that Y will win is 1/12 and that Z will win is 1/7. Assuming that a dead heat is impossible, find the chance that one of them will win.
Select the correct option
A) 1 / 140
B) 10 / 21
C) 27 / 410
D) 11 / 21
E) 57 / 120

Rationale: "required probability = p ( x ) + p ( y ) + p ( z ) ( all the events are mutually exclusive ) . = 1 / 4 + 1 / 12 + 1 / 7 = 10 / 21 answer : b"
Answer: B