Question

a teacher is experimenting with a new computer - based instruction and conducts a study to test its effectiveness. in which situation could the teacher use the two - sample t - test for comparing two population means?
a. the teacher uses a combination of traditional methods and computer - based instruction. she asks students which they liked better. she wants to determine if the majority prefer the computer - based instruction.
b. the teacher randomly divides the class into two groups. one of the groups receives computer - based instruction and the other group receives traditional instruction without computers. after instruction, each student takes a test and the teacher wants to compare the test scores of the two groups.
c. the teacher gives each student in the class a pretest. then she teaches a lesson using a computer program. afterwards, she gives each student a post - test. the teacher wants to compare test scores for each student to see whether the data will show an improvement.

Explanation:

• Option A: This is about proportions (majority preference) not means. A two - sample t - test is for comparing means, so this option is incorrect.
• Option B: Here, we have two independent groups (one with computer - based instruction and one with traditional instruction). The teacher wants to compare the test scores (which are quantitative, so we can talk about means) of these two independent groups. This is a classic case for a two - sample t - test.
• Option C: This is a paired - samples situation (pre - test and post - test for the same students). A paired - t - test (not a two - sample t - test) is appropriate for comparing the means of two related samples.

Answer:

B. The teacher randomly divides the class into two groups. One of the groups receives computer - based instruction and the other group receives traditional instruction without computers. After instruction, each student takes a test and the teacher wants to compare the test scores of the two groups.