The length of steel bolts produced by a machine is normally distributed with a mean of 50.0 mm and a standard deviation of 0.8 mm.
Find the probability of a bolt being longer than 51.5 mm.
The technician suspects that the mean length of the bolts has changed.
Write down a null and alternative hypothesis for a two-tailed test.
A sample of 16 bolts is measured and the mean length is found to be 50.5 mm.
Test at the 10% significance level whether there is evidence that the mean length has changed.
284 exam-style questions on CCEA A Level Maths 4.5 Statistical distributions (A-level only), covering 4.5.1 Statistical distributions (A-level only) and 4.5.2 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.