Fast-food restaurant chains like Whataburger are replacing cashiers with touch-screen ordering kiosks. Currently, the marginal product of another cashier is 48 customers served per hour; the marginal product of another kiosk is 32 customers served per hour. A cashier can be hired fora wage of $15; a kiosk rents for $12.

1. Is Whataburger using the optimal cost-minimizing mix of cashiers and kiosks? Explain.

(b) What can Whataburger do to improve its mix of inputs - hire more cashiers or fewer? Rent more kiosks or fewer?