A manufacturer takes two simple random samples from a large batch of rechargeable batteries. In sample A, 9 of 150 batteries fail a capacity test. In sample B, 4 of 60 batteries fail the test.
Calculate the estimated failure proportion from each sample.
A manager says, "Sample B proves that the batch has become less reliable." Criticise this statement.
The two samples are combined. Calculate the estimated failure proportion for the combined sample.
36 exam-style questions on WJEC A Level Maths 2.1 Statistical Sampling, covering 2.1.1 Statistical Sampling, 2.1.2 Statistical Sampling, 2.1.3 Statistical Sampling, 2.1.4 Statistical Sampling, and 2.1 Statistical Sampling. Each one has a worked solution and a mark scheme showing where the marks go.