| Exam Board | CAIE |
|---|---|
| Module | S2 (Statistics 2) |
| Year | 2017 |
| Session | November |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Hypothesis test of a normal distribution |
4 The lengths, in millimetres, of rods produced by a machine are normally distributed with mean $\mu$ and standard deviation 0.9. A random sample of 75 rods produced by the machine has mean length 300.1 mm .\\
(i) Find a $99 \%$ confidence interval for $\mu$, giving your answer correct to 2 decimal places.\\
The manufacturer claims that the machine produces rods with mean length 300 mm .\\
(ii) Use the confidence interval found in part (i) to comment on this claim.\\
\hfill \mbox{\textit{CAIE S2 2017 Q4}}