Moderate -0.8 This is a straightforward confidence interval calculation using the normal distribution with known variance. It requires only direct substitution into the standard formula (x̄ ± z*σ/√n) with no conceptual challenges, making it easier than average but not trivial since it involves a large sample and 99% confidence level requiring correct z-value lookup.
1 Packets of fish food have weights that are distributed with standard deviation 2.3 g . A random sample of 200 packets is taken. The mean weight of this sample is found to be 99.2 g . Calculate a \(99 \%\) confidence interval for the population mean weight.
1 Packets of fish food have weights that are distributed with standard deviation 2.3 g . A random sample of 200 packets is taken. The mean weight of this sample is found to be 99.2 g . Calculate a $99 \%$ confidence interval for the population mean weight.
\hfill \mbox{\textit{CAIE S2 2006 Q1 [3]}}