The mean time it takes for a specific make/model of watch to break down and need repair services from manufacturer is 30 months, with a standard deviation of 8 months. The manufacturer's warranty for the watch is 1 year (12 months). Suppose normal distribution. To be more customer-friendly, the manufacturer has decided to change its warranty policy so the probability of service while under warranty is 0.03 or less. How many months should be set as the warranty period?