In Spring 2017, data was collected from a random selection of STA 2023 students. One of the questions asked how many hours they had volunteered in the past 24 hours. For the 39 randomly selected upperclassmen, the sample mean was 0.12 and sample standard deviation was 0.42. For the 35 randomly selected underclassmen, the sample mean was 0.34 and the sample standard deviation was 0.87. What is the point estimate of the difference in the population mean volunteered between underclassmen and upperclassmen?

Answer: 0.22Step-by-step explanation:We know that the best point estimate for the difference between two population mean is the difference between their sample means.Given : For the 39 randomly selected upperclassmen, the sample mean was 0.12 and sample standard deviation was 0.42. For the 35 randomly selected underclassmen, the sample mean was 0.34 and the sample standard deviation was 0.87. Let A denotes the population of upperclassmen and B denotes the population of underclassmen . [tex]\overline{x}_A=0.12[/tex][tex]\overline{x}_B=0.34[/tex]Then, the point estimate of the difference in the population mean volunteered between underclassmen and upperclassmen will be :-[tex]\overline{x}_B-\overline{x}_A=0.34-0.12=0.22[/tex]Hence, the point estimate of the difference in the population mean volunteered between underclassmen and upperclassmen =0.22