StatisticsdrillOne-proportion z test
A statistics problem from Statisticsdrill. Solve it with one answer box, with a fresh sample on every attempt and the worked steps and spreadsheet function in the answer, and it is checked the moment you submit.
The task
A site's long-run conversion rate is 5%. After a redesign, 20 of 200 visitors convert. Find the z statistic for H0: p = 0.05 against H1: p ≠ 0.05, using the hypothesized rate in the standard error, then decide at α = 0.1. Round to 2 decimal places.
What this problem teaches
z = (p̂ - p0) / √(p0(1 - p0) / n). Under H0 the true rate is p0, so the standard error is built from p0, not from p̂.
A hint if you get stuck
z = (p̂ - p0) / √(p0(1 - p0) / n). Under H0 the true rate is p0, so the standard error is built from p0, not from p̂.
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