What is the test for admitting evidence of prior bad acts under Rule 404(b)?

We review for abuse of discretion a district court's decision to admit evidence of prior bad acts under 404(b). United States v. Mayans, 17 F.3d 1174, 1181 (9th Cir.1994).

Federal Rule of Evidence 404(b) allows evidence of "other crimes" to establish "motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident." Rule 404(b) evidence is admissible if: (1) it tends to prove a material point; (2) the prior bad act is not too remote in time; (3) the evidence is sufficient to support a finding that the defendant committed the other acts; and (4) the acts are similar to the charged offense. Id.; United States v. Garcia-Orozco, 997 F.2d 1302, 1304 (9th Cir.1993).

When attempting to establish relevance, the government " 'must articulate precisely the evidential hypothesis by which a fact consequence may be inferred from the other acts evidence.' " Mayans, 17 F.3d at 1181 (quoting United States v. Mehrmanesh, 689 F.2d 822, 830 (9th Cir.1982)). Where, as here, the government's theory of admissibility is to show the defendant's knowledge, there must be "a logical connection between the knowledge gained as a result of the commission of the prior act and the knowledge at issue in the charged act." Mayans, 17 F.3d at 1181-82. If a prior act is offered to show knowledge, however, it "need not be similar to the charged act as long as the prior act was one which would tend to make the 'existence of the defendant's knowledge more probable than it would be without the evidence.' " United States v. Santa-Cruz, 48 F.3d 1118, 1119 (9th Cir.1995) (quoting United States v. Arambula-Ruiz, 987 F.2d 599, 603 (9th Cir.1993)).