Question 1191976
Here's the breakdown of the answers:

**(a) Which times are selected in the sample?**

The problem states that the number of patients in *every 3-hour period* is selected.  So, the following starting times are selected:

* 9 am
* 12 nn (12 pm)
* 3 pm
* 6 pm

**(b) What is the sampling method used?**

This is *systematic sampling*.  The data is arranged in a sequence (time), and every *k*th element (in this case, every 3-hour period) is selected.

**(c) What is the average number of persons per hour based on the times selected in the sample?**

1. **Identify the number of persons for each selected time:**
   * 9 am: 29 persons
   * 12 nn: 14 persons
   * 3 pm: 48 persons
   * 6 pm: 33 persons

2. **Calculate the total number of persons in the sample:** 29 + 14 + 48 + 33 = 124 persons

3. **Calculate the total number of hours represented by the sample:** 4 time periods * 3 hours/period = 12 hours

4. **Calculate the average number of persons per hour:** 124 persons / 12 hours = 10.33 persons/hour (approximately)