Compute the value of the ????-value for each of the following values of ????obs for a large sample ????-test for the difference of two proportions.

(a) ????0 ∶ ???????? ≤ ???????? and ????obs = 1.38.

(b) ????0 ∶ ???????? ≥ ???????? and ????obs = −2.38.

(c) ????0 ∶ ???????? = ???????? and ????obs = 2.98.