Wholemark is an Internet order business that sells one popular New Year's greeting card once a year. The cost of the paper on which the card is printed is $$0\mathrm{.}10$ per card, and the cost of printing is $$0\mathrm{.}42$ per card. The company receives $$2\mathrm{.}40$ 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 a mean of $2,500$ and a standard deviation $600.($Assume these four are independent.$)$ What is the optimal production quantity for the card? $($Use Excel's NORM.S$.$INV$()$ function to find the z value. Round z value to $2$ decimal places. Round your answer to the nearest whole number.$)$