If your null and alternative hypothesis are:

Question

H_0 : μ_1 = μ_2
H_1 : μ_1 ≠ μ_2

Then the test is:
A. left tailed
B. two tailed
C. right tailed

Answer 1

The correct answer is:

B. two tailed

In a two-tailed test, you are checking for differences in both directions (i.e., whether μ_1 is either greater than or less than μ_2). Since your alternative hypothesis (H_1) states that μ_1 is not equal to μ_2, it indicates that you are looking for a difference in both directions, which makes it a two-tailed test.