The durations of the calls are given as: 9, 2, 3, 1, and 5 minutes.
Step 1: Compute the total time spent on all calls: \[ 9 + 2 + 3 + 1 + 5 = 20 \text{ minutes} \]
Step 2: Determine the number of calls: \[ \text{Total calls} = 5 \]
Step 3: Calculate the average time per call: \[ \frac{20}{5} = 4 \text{ minutes} \] Thus, the average duration of a call is 4 minutes.