Question

At CDE dental office, on average, 30 patients arrive every hour and are processed at the same rate. Patients wait in line for registration. On average, it takes 5 minutes for registration, not including waiting time. A dentist’s assistant sees a patient after registration and assigns the patient to one of the two tracks, one for routine cleanings and another for major treatments. On average, the dentist's assistant spends 20 minutes with each patient. On average, 2/3 (or 66.67%) of the patients are classified by the dentist’s assistant as needing routine cleanings. Patients for routine cleaning are seen by a hygienist who cleans their teeth and releases them. On average, this takes 30 minutes. Patients for major treatment are seen by a dentist for further treatment. On average, this takes 1 hour. It is observed that there are, on average, 5 people waiting to be registered, 10 waiting to be seen by the dentist’s assistant, 15 waiting to be seen by a hygienist in the routine cleaning area, and 15 waiting to be seen by a dentist in the major treatment area. What percentage is the flow-time efficiency of a patient for major treatment? Number only without % sign.

Answer 1

Process Flow Chart

The theoretical flow time (in minutes) of a patient for routine cleaning = 5+20+30 = 55 minutes

The theoretical flow time (in minutes) of a patient for major treatment = 5+20+60 = 85 minutes

The average waiting time (in minutes) to be seen by a dentist = I / R = 15/10 hrs = 90 minutes

The average waiting time (in minutes) to be seen by the dentist’s assistant = I / R = 10/30 hrs. = 20 minutes

The average waiting time (in minutes) to be seen by the registration = I / R = 5/30 hrs. = 10 minutes

The flow-time efficiency of a patient for major treatment = Theoretical flow time / Actual flow time = 85 / (85+90+20+10) = 41.46%

The average waiting time (in minutes) to be seen by a hygienist = I / R = 15/20 hrs. = 45 minutes