Moderate -0.3 This is a straightforward one-sample z-test with clearly stated hypotheses, given variance, and standard significance level. It requires only routine application of the z-test formula and comparison to critical values—no conceptual challenges or multi-step problem-solving. Slightly easier than average due to its mechanical nature, though the context and calculation keep it from being trivial.
10 In the past, the time spent in minutes, by customers in a certain library had mean 32.5 and standard deviation 8.2.
Following a change of layout in the library, the mean time spent in the library by a random sample of 50 customers is found to be 34.5 minutes.
Assuming that the standard deviation remains at 8.2 , test at the \(5 \%\) significance level whether the mean time spent by customers in the library has changed.
10 In the past, the time spent in minutes, by customers in a certain library had mean 32.5 and standard deviation 8.2.
Following a change of layout in the library, the mean time spent in the library by a random sample of 50 customers is found to be 34.5 minutes.
Assuming that the standard deviation remains at 8.2 , test at the $5 \%$ significance level whether the mean time spent by customers in the library has changed.
\hfill \mbox{\textit{OCR H240/02 Q10 [7]}}