PMF and CDF Worksheet Define X and units: Support: PMF validity checks: Sorted x and p(x) table: F(x)=P(X<=x): Exactly x: At most x: Fewer than x=P(X<=x-1): More than x=1-F(x): At least x=1-F(x-1): Interpretation: Original educational material created for STATLAB Academy. Textbooks may be used only as curriculum references.