1. **Problem statement:** A manufacturer shipped 53 cameras, 4 of which are defective. The store sold 30 cameras before discovering defects. We want the probability that at least one defective camera was sold. 2. **Formula and explanation:** The hint gives the probability that no defective cameras were sold as $$\frac{\binom{49}{30}}{\binom{53}{30}}$$ where 49 is the number of non-defective cameras. 3. **Key rule:** Probability that at least one defective camera was sold is the complement of no defective cameras sold: $$P(\text{at least one defective}) = 1 - P(\text{no defective})$$ 4. **Calculate:** - Total cameras: 53 - Defective: 4 - Non-defective: 49 - Cameras sold: 30 5. **Evaluate the probability no defective cameras sold:** $$P(\text{no defective}) = \frac{\binom{49}{30}}{\binom{53}{30}}$$ 6. **Final answer:** $$P(\text{at least one defective}) = 1 - \frac{\binom{49}{30}}{\binom{53}{30}}$$ This formula gives the probability that at least one defective camera was sold out of the 30 sold cameras.