Determine the critical value that would be used to test the null hypothesis for the following situations using the classical approach and the sign test:
a. Ho: P(+) = 0.5 vs. Ha: P(+) = 0.5, with n = 18 and a = 0.05
b. Ho: P(+) = 0.5 vs. Ha: P(+)0.5, with n = 78 and a = 0.05
c. Ho: P(+) = 0.5 vs. Ha: P(+) 0.5, with n = 38 and a = 0.05
d.. Ho: P(+) = 0.5 vs. Ha: P(+) = 0.5, with n = 148 and a = 0.05