To find the test statistic or z-score given sample number (n), sample mean (x), standard deviation (σ), and population mean (μ), we can use
[tex] z-score = \frac{x - \mu }{\sigma / \sqrt{n}} [/tex]
Given that n = 36, x = 24.6, μ = 20, and σ = 12,
[tex] z-score = \frac{24.6 - 20}{12 / \sqrt{36}} [/tex]
[tex] z-score = \frac{4.6}{2} = 2.3 [/tex]
From this, we see that the test statistic is 2.3.
Answer: 2.3
