You have purchased two different batches of laptops from the same vendor; both batches are supposed to be exactly the same model, with exactly the same configuration. You suspect, however, that the two batches are not configured the same! To investigate, you run benchmarks on the laptops from each batch; if the batches are different models, then the benchmark scores might be different. On a sample of twenty laptops from batch 1, you get a mean benchmark score of 1801; for a sample of twenty from batch 2, you get 1792. The standard deviation for benchmark scores for a given model should be low; assume that the known standard deviation for each population is 24.

For this question, perform your calculation using the formulas. Use the numbers given for the batches as the population numbers--do not swap them.

What is the point estimate for the difference in the population means (to three decimal places)