The average number of days required by a college's undergraduate students to complete a project was 22 days in the previous year. The college administration wishes to determine whether the average differs this year. A sample of 169 students produced a sample mean of 18 days this year, with a sample standard deviation of 26 days. Assume that the number of days to complete the project is normally distributed. Compute the observed significance (the p-value) of the test.