If Two Populations Are Not Known to Be Normally Distributed $\bar { X } _ { 1 } - \bar { X } _ { 2 }$

question 20

Multiple Choice

If two populations are not known to be normally distributed, the sampling distribution of the sample mean difference, $\bar { X } _ { 1 } - \bar { X } _ { 2 }$ , will be:

• A) normally distributed only if both population sizes are greater than 30.
• B) normally distributed.
• C) normally distributed only if at least one of the sample sizes is greater than 30.
• D) approximately normally distributed.