A searchlight on top of the watch-tower makes 2 revolutions per minute. What is the probability that a man appearing near the tower will stay in the dark for at least 5 seconds?	Choose the most appropriate option
A) 1 / 4	B) 1 / 3	C) 1 / 2	D) 2 / 3	E) 5 / 6

Rationale: 2 revolutions per minute = 1 revolution every 30 seconds so no matter what anybody appearing at the tower can not stay in the dark for more than 30 seconds . this will be our total number of possibilities i . e the denominator . p ( man in dark for at least 5 seconds ) = 1 - p ( man in dark for max of 5 seconds ) = 1 - 5 / 30 = 1 - 1 / 6 = 5 / 6 or the other way would be : p ( man in dark for at least 5 seconds ) is like saying he can be in dark for 5 , 6,7 . . . all the way to 30 seconds because that is the max . in this approach it would be 25 / 30 seconds = 5 / 6 . answer is e
Answer: E