Manufacture of the certain component needs three different machining operations. Machining time for each operation has normal distribution, and the three times are independent of one another. The mean values are 15, 20, and 30 min, respectively, and standard deviations are 2, 1, and 1.7 min, respectively. Determine the probability that it takes at most 1 hour of machining time to produce randomly selected component? (Round your answer to four decimal places.)