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 12 seconds ?
"the searchlight completes one revolution every 15 seconds . the probability that the man ' s area will be lit up is 12 / 15 = 4 / 5 . the probability that he will stay in the dark is 1 - 4 / 5 = 1 / 5 the answer is e ."
subtract(const_1, divide(12, multiply(12, const_3)))