1. The problem asks for the probability of picking a prime number card from the given set: 3, 4, 5, 6, 7, 8, 9. 2. Identify the prime numbers in the set. Prime numbers are numbers greater than 1 that have no divisors other than 1 and themselves. 3. The prime numbers here are 3, 5, and 7. 4. Count the total number of cards: there are 7 cards in total. 5. Count the number of prime cards: there are 3 prime cards. 6. Calculate the probability of picking a prime card: $$P(\text{prime}) = \frac{\text{number of prime cards}}{\text{total number of cards}} = \frac{3}{7}$$ 7. Convert the probability to a percentage: $$\frac{3}{7} \times 100 = 42.857...\%$$ 8. Round to the nearest tenth: $$42.9\%$$ Final answer: The probability of picking a prime card is **42.9%**.