20871
Idle times The mean stationary idle time of the queue ( period with 0 customers ) is β – 1 / μ , with variance ( 1 + δ − 2μβδ ) / μ2 ( 1 – δ ) .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None