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prof. P.Cremonesi Esame Di Impianti 2012-06- 27.Docx Last name / Cognome First name / Nome Matricola Grade / Voto Exam duration: 2 hours If the exam is completed at least 15 minutes in advance, the student will receive one extra bonus of 1 point. Students can use pen or pencil to write answers. Please, do not write answers in red color. Students are permitted to use a non-programmable calculator. Students are NOT permitted to copy anyone else’s answers, pass notes amongst themselves, bring sheets, take the exam on behalf of someone else or engage in other forms of misconduct at any time during the exam. Violators shall receive a zero grade for the exam. Students are NOT permitted to use mobile phones and similar connected devices. If any of such devices will be discovered in the vicinity of a student, the student shall receive a zero grade for the exam. Question 1 Esame Di Impianti 2012-06- 27.Docx Score (3 punti) Performance By monitoring a single class iteractive system, we are able to measure the following data: - Monitoring period: 1hour - CPU demand: 0,3seconds/transaction - CPU utilization: 30% - Response time: 20seconds/transaction - Number of users: 60 Which is the average think time of these users? Question 2 Esame Di Impianti 2012-06- 27.Docx Score (3 punti) Performance Consider a closed queuing network with the following characteristics: - number of stationsK =3 - service demand D1 = 2 - service demand D2 = 4 - service demand D3 = 6 - think time Z =6 - number of users N =4 Which are the lower and upper bounds of the response time? Question 3 Esame Di Impianti 2012-06- 27.Docx Score (3 punti) Affidabilità Spiegare qual è la differenza tra failure rate e densità di probabilità di guasto. Mostrare quale relazione analitica esiste tra le due grandezze. Question…