20 A medical researcher treats 16 subjects with high blood pressure by Increasing their physical activity and changing their diet. The average decrease in blood pressure reading Is 20 after 3 months of this treatment plan. Assume that the decrease in blood pressure after 3 months of participating in the treatment plans follows a normal distribution, with unknown mean ( and population standard deviation of 10. A 79% confidence interval for it is 20 + 10 20 # 6,45 00 00 20 7.30 20 + 7.37 21 A student is conducting research on people's favorite genre of movies. The students select the first 25 students that walk into our history course to be the study, This overall sample Is O convenience sampling simple random sampling stratified random sampling OO Voluntary response sampling