Premise:
"I suppose, said Lawrence quietly, "that I should.""
Hypothesis: Lawrence thought that he probably should have done it.

yes

Premise:
"In fact, that same opportunity is available to every other corporate manager in the industry as well, and they're rejecting it too (remember that discrimination must be widespread or all blacks would move to nondiscriminatory firms)."
Hypothesis: Black corporate managers feel there is discrimination in all firms.

it is not possible to tell

Premise:
"As far as I can remember in June or July of 1915."
Hypothesis: This happened in the year 2015.
no