# Question: If the number of minutes that a doctor spends with

If the number of minutes that a doctor spends with a patient is a random variable having an exponential distribution with the parameter θ = 9, what are the probabilities that it will take the doctor at least 20 minutes to treat

(a) One patient;

(b) Two patients;

(c) Three patients?

(a) One patient;

(b) Two patients;

(c) Three patients?

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