A car dealer in KC specializes in selling cars from a Japanese manufacturer. The manufacturer is launching a new model this year and any order for this model placed by the dealer is fulfilled after a leadtime of 1 month. The dealer forecasts that the monthly demand for this new model will be Normally distributed with a mean of 20 and a standard deviation of 10, and wishes to maintain a service level of 0.75. 

What base-stock level should the dealer choose to achieve a service level of 0.75? If your answer is not an integer, provide at least three decimal places, e.g., 7.500.