A manufacturer of t-shirts marks a shirt as irregular when it has defects such as crooked seams, stains, rips, or holes. A small number of irregular t-shirts are expected as part of the manufacturing process, but if more than 8% of the t-shirts manufactured at a plant are classified as irregular, the manager has to do an investigation to try to find the source of the increased mistakes in the manufacturing process.

In order to test whether his plant is making a higher than expected number of irregular t-shirts, the manager of a plant randomly selects 100 t-shirts and finds that 12 are irregular.

He plans to test the hypotheses: H₀, P = 0.08, versus H_a, p > 0.08 (where p is the true proportion of irregular t-shirts). What is the test statistic?

Z = 1.23Z = 1.47Z = 5Z = 1.47