To obtain the mean number of calls per minute, we need to calculate the weighted average of the number of calls and their corresponding frequencies.

The formula to calculate the mean is:

Mean = (Σ (Number of Calls * Frequency)) / (Σ Frequency)

Using the given frequency distribution:

Number of Calls: 0 1 2 3 4 5 6 7 Frequency: 14 21 25 43 51 40 39 12

We can calculate the mean as follows:

Mean = (014 + 121 + 225 + 343 + 451 + 540 + 639 + 712) / (14 + 21 + 25 + 43 + 51 + 40 + 39 + 12)

Mean = (0 + 21 + 50 + 129 + 204 + 200 + 234 + 84) / 245

Mean = 922 / 245

Mean ≈ 3.76

Therefore, the mean number of calls per minute is approximately 3.76.

This is a discrete frequency distribution because the number of calls is a discrete variable. It can only take on specific whole number values (0, 1, 2, 3, etc.) and cannot have fractional or continuous values.