Posted by Delilah on Friday, March 29, 2013 at 9:59pm.
in #1 - 3 you don't state what the event is, so those questions are incomplete
#4. Odds in favour of some event
= prob of the event / prob of not the event
prob of correct choice = 1/5
so the odds in favour of picking the right answer
= (1/5 / 4/5)
= 1/4
or 1 : 4