A manufacturer of high-precision capacitors specifies that the mean capacitance of a specific model is 14.50 μF14.50\, \mu \text{F}14.50μF. A quality control engineer believes that a recent manufacturing fault has resulted in a lower mean capacitance than specified. A random sample of 81 capacitors is tested, yielding a sample mean of 14.38 μF14.38\, \mu \text{F}14.38μF and a standard deviation of 0.45 μF0.45\, \mu \text{F}0.45μF. Test the engineer's belief at the 1% level of significance. State your hypotheses clearly.
130 exam-style questions on WJEC A Level Maths 4.3.2 Statistical hypothesis testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.