The problem appears to involve performing a hypothesis test to compare prices of textbooks at bookstores (Population 1) and online retailers (Population 2). We are likely using a paired sample t-test since the same textbooks are priced at both locations. The null hypothesis $H_0$ would be that there is no significant difference in prices between bookstores and online retailers, and the alternative hypothesis $H_1$ is that prices are less expensive online.

Here are the steps to compute the test statistic for a paired t-test:

1. Calculate the differences between the paired values (prices at bookstore minus prices at the online retailer).
2. Compute the mean difference ($\bar{d}$).
3. Compute the standard deviation of the differences ($s_d$).
4. Calculate the test statistic using the formula: $t = \frac{\bar{d}}{s_d / \sqrt{n}}$ where $n$ is the number of pairs (in this case, 25).

Let me now calculate this.The value of the test statistic is approximately $t = 1.314$ (rounded to three decimal places).

Would you like a detailed explanation of how this was calculated, or do you have any other questions?

Here are five related questions to consider:

1. What are the null and alternative hypotheses for this test?
2. How do you interpret the result of a paired t-test?
3. How would the test statistic change if there were more textbooks in the sample?
4. How does changing the significance level ($\alpha$) affect the test conclusion?
5. What would be the next step after computing the test statistic?

Tip: Always check the assumptions of the t-test, such as normality of the differences, especially when the sample size is small.