Whole mark is an Internet order business that sells one popular New Year greeting card once a year. The cost of the paper on which the card is printed is $ 0.05 per card, and the cost of printing is $ 0.15 per card. The company receives $ 2.15 per card sold. Since the cards have the current year printed on them, unsold cards have no salvage value. Its customers are from the four areas: Los Angeles, Santa Monica, Hollywood, and Pasadena. Based on past data, the number of customers from each of the four regions is normally distributed with mean 2,000 and standard deviation 500. (Assume these four are independent.) What is the optimal production quantity for the card?