A quality control inspection of smart sensors found that 710\frac{7}{10}107 of the units pass a high-temperature stress test. During a separate evaluation, it was determined that 25\frac{2}{5}52 of the units pass a moisture-resistance test. Among the units that pass the high-temperature stress test, it was found that only 310\frac{3}{10}103 also pass the moisture-resistance test.
Find the probability that a randomly selected sensor from this inspection:
Passes both the high-temperature stress test and the moisture-resistance test.
Does not pass the high-temperature stress test and does not pass the moisture-resistance test.
Determine, giving your reason, whether or not passing the high-temperature stress test and passing the moisture-resistance test are statistically independent.
200 exam-style questions on OCR (MEI) A Level Maths 2.3 Probability, covering 2.3.1 Calculate the probability of an event, 2.3.2 Complementary events, 2.3.3 Expected frequency of an event, 2.3.4 Diagrams to calculate probabilities, 2.3.5 Mutually exclusive and independent events, 2.3.6 Add probabilities for mutually exclusive events, 2.3.7 Multiply probabilities for independent events, 2.3.8 Mutually exclusive and independent events (notation) (A-level only), 2.3.9 Venn diagrams for probabilities (A-level only), 2.3.10 Conditional probabilities (A-level only), and 2.3.11 Independence via conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.