If the underlying populations cannot be assumed to be normal, then by the central limit theorem, the sampling distribution of xbar1-xbar2 is approximately normal only if both sample sizes are sufficiently largethat is, when _________ .

Multiple Choice

• n₁+n₂= 30
• n₁= 30andn₂= 30
• n₁+n₂ 30
• n₁ 30andn₂ 30