The times taken for worker 1 to perform a task are independently distributed as a normal distribution with mean 13 minutes and standard deviation 0.5 minutes. The times taken for worker 2 to perform a task are independently distributed as a normal distribution with mean 17 minutes and standard deviation 0.6 minutes, and they are independent of the times taken by worker 1. At the beginning of the day, both workers start their first task at the same time, and when they have finished a task, they immediately start another task. What is the probability that worker 1 will finish his fourth task before worker 2 has finished his third task?