Historically, the proportion of students entering a university who finished in 4 years or less was 64%. To test whether this proportion has decreased, 122 students were examined and 50% had finished in 4 years or less. To determine whether the proportion of students who finish in 4 year or less has statistically significantly decreased (at the 5% level of signficance), what is the test statistic? (please round your answer to 2 decimal places)