DELAYED EXPONENTIAL CALLS SERVED IN RANDOM ORDER 373 



■0.001 



2.5 



5.0 7.5 10.0 12.5 15.0 17.5 20.0 



t/h = DELAY IN MULTIPLES OF AVERAGE HOLDING TIME 



22.5 



Fig. 11 

 c = 4. 



Delaj^ed traffic served in random order, exponential holding times, 



ILLUSTRATIVE EXAMPLES 



Example No. 1 



A 20-trunk toll route carrying exponentially distributed holding time 

 calls with average length of 5 minutes, is loaded with 16.0 erlangs of traf- 

 fic, and any calls delayed wall be served in random order. What per cent 

 of all calls mil be delayed? What per cent will be delayed more than 5 

 minutes? More than 10 minutes? 



16 

 Solution. Enter Fig. 16 (the c = 20 chart) and read on the a = — = 



0.80 occupancy curve. At t/h = 0, the per cent of all calls delayed is 

 found to be 26 per cent. At t/h = 1, the calls having delays exceeding 1 

 holding time, or 5 minutes, are 1.2 per cent, and at t/h = 2, the calls 

 with delays exceeding 10 minutes are 0.2 per cent. 



