Suppose the following hypotheses are to be tested.

H₀ : _A = _B and H₁: _{A B}

for two populations in which the population variances are not known.

Two samples of sizes 40 and 35 respectively were collected. The data were not paired. Which hypothesis test should be used?

(You may assume that any additional requirements for your selected test, such as normality and/or equal population variances are satisfied.)

• One-sample t-test
• Two-sample t-test
• test for contingency tables
• Matched-pairs t-test
• One-sample z-test
• Two-sample z-test
• Sign test