Suppose for all Apple iPhone users the mean time to type a standard text message is 34.7 seconds with a standard deviation of 11.2 seconds. Additionally, suppose for all Samsung Galaxy users the mean time to type a standard text message is 40.6 seconds with a standard deviation of 12.7 seconds. If a simple random sample of 95 Apple iPhone users is selected and _{X1 bar} X1 bar= the mean time to type the standard text message is determined, and if an independent simple random sample of 105 Samsung Galaxy users is selected and X2 bar the mean time to type the standard text message is determined, if appropriate describe completely the sampling distribution of_{. X1-X2}