Random Sample and Margin of Error {SAT}

A research assistant randomly selected 75 undergraduate students from the list of all students enrolled in the psychology-degree program at a large university. She asked each of the 75 students, “How many minutes per day do you typically spend reading?” The mean reading time in the sample was 89 minutes, and the margin of error for this estimate was 4.28 minutes. Another research assistant intends to replicate the survey and will attempt to get a smaller margin of error. Which of the following samples will most likely result in a smaller margin of error for the estimated mean time students in the psychology-degree program read per day?
​
A.)  40 randomly selected undergraduate psychology-degree program students
B.)  40 randomly selected undergraduate students from all degree programs at the college
C.)  300 randomly selected undergraduate psychology-degree program students
D.)  300 randomly selected undergraduate students from all degree programs at the college

---

If a smaller margin of error is desired,
1.) The selected population should remain within the psychology-degree program,
thus eliminating answers B and D

2.)  A larger selected group would produce a smaller margin of error, compared to the margin of error likely increasing if a smaller group is chosen, thus eliminating answer A

C.)  300 randomly selected undergraduate psychology-degree program students

Ask Algebra House