Moderate -0.3 This is a straightforward one-sample z-test with all information clearly provided (n=80, x̄=58.9, σ=5.0, α=0.05). Students need to set up hypotheses (H₀: μ=60 vs H₁: μ<60), calculate the test statistic z = (58.9-60)/(5/√80) ≈ -1.96, and compare to the critical value. It's slightly easier than average because it's a standard textbook procedure with no complications, though it does require correct execution of multiple steps.
8. 80 randomly chosen people are asked to estimate a time interval of 60 seconds without using a watch or clock. The mean of the 80 estimates is 58.9 seconds. Previous evidence shows that the population standard deviation of such estimates is 5.0 seconds. Test, at the \(5 \%\) significance level, whether there is evidence that people tend to underestimate the time interval. [0pt]
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8. 80 randomly chosen people are asked to estimate a time interval of 60 seconds without using a watch or clock. The mean of the 80 estimates is 58.9 seconds. Previous evidence shows that the population standard deviation of such estimates is 5.0 seconds. Test, at the $5 \%$ significance level, whether there is evidence that people tend to underestimate the time interval.\\[0pt]
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\hfill \mbox{\textit{SPS SPS SM Statistics 2025 Q8 [7]}}