An industrial assembly hall is continuously lighted by one hundred 40- W mercury vapor lamps supplied by a 120- V and 60- Hz source with a power factor of 0.65. Due to the low power factor, a 25 percent penalty is applied at billing. If the average price of 1 kWh is $ 0.01 and the capacitor's average price is $ 50 per millifarad, compute after how many days of operation the penalty billing covers the price of the power factor correction capacitor. ( To avoid penalty, the power factor must be greater than 0.85.)