94 



BELL SYSTEM TECHNICAL JOURNAL 



X 30 40 so TO /O eo 30 40 30 70 /CO 



DOLLARS RENT PER MONTH 



20 30 *0 SO 70 70 20 30 *0 SO 70 lOO 



DOLLARS RENT PER MONTH 



40 50 TO 100 



Fig. 3 



