On a swim team of 150, ten of the 28 novices practise four times a week and 80 members do so in all. Are being a novice and practising four times a week independent?

1. The joint probability is the 10 novices who practise four times a week divided by 150, which is 0.0667. 2. The probability of being a novice is 28 divided by 150, which is 0.1867. 3. The probability of practising four times a week is 80 divided by 150, which is 0.5333. 4. Multiplying those two gives 0.0996. 5. Since 0.0667 does not equal 0.0996, the two events are not independent. 6. Being close in size is not the test, so a near miss between the two figures still means dependence. _Source: OpenStax Introductory Business Statistics (CC BY 4.0), Ch 3 "Probability Topics", section 3.3 Two Basic Rules of Probability_