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 students must recall the correct z-value for 98% confidence and perform accurate arithmetic.
1 The weights, in grams, of packets of sugar are distributed with mean \(\mu\) and standard deviation 23. A random sample of 150 packets is taken. The mean weight of this sample is found to be 494 g . Calculate a 98\% confidence interval for \(\mu\).
1 The weights, in grams, of packets of sugar are distributed with mean $\mu$ and standard deviation 23. A random sample of 150 packets is taken. The mean weight of this sample is found to be 494 g . Calculate a 98\% confidence interval for $\mu$.
\hfill \mbox{\textit{CAIE S2 2012 Q1 [3]}}