A searchlight on top of the watchtower makes 4 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 correct choice from the following options
A) 5/6
B) 4/5
C) 3/4
D) 2/3
E) 1/2
The searchlight completes one revolution every 15 seconds.   The probability that the man's area will be lit up is 5/15=1/3.   The probability that he will stay in the dark is 1-1/3=2/3   The answer is 2/3.
<result>D</result>
A searchlight on top of the watchtower makes 4 revolutions per minute. What is the probability that a man appearing near the tower will stay in the dark for at least 5 seconds?