1. **State the problem:** We need to determine the type of sampling method used in each of the four scenarios described. 2. **Recall common sampling methods:** - **Random sampling:** Every member of the population has an equal chance of being selected. - **Non-random (convenience) sampling:** Samples are selected based on ease of access or availability. - **Stratified sampling:** Population is divided into subgroups (strata) and samples are taken from each. - **Snowball sampling:** Existing study subjects recruit future subjects from among their acquaintances. - **Voluntary response sampling:** Participants volunteer themselves to be part of the sample. 3. **Analyze each scenario:** **Scenario 1:** A sports equipment company selects a non-random sample of 30 males and 20 females aged 21-35 at a gym. - This is a **non-random (convenience) sampling** because the sample is taken from people available at the gym, not randomly selected. **Scenario 2:** A wholesaler surveys 50 Muslims by approaching people wearing Malay costume in a mall. - This is also **convenience sampling** because the sample is chosen based on visible characteristics and location, not randomly. **Scenario 3:** A research team selects a stamp collector at random and asks them to refer other collectors. - This is **snowball sampling** since initial subjects recruit others. **Scenario 4:** A professor uses student volunteers for research. - This is **voluntary response sampling** because participants self-select to join. 4. **Summary:** - Scenario 1: Non-random (convenience) sampling - Scenario 2: Convenience sampling - Scenario 3: Snowball sampling - Scenario 4: Voluntary response sampling This classification helps understand the potential biases and representativeness of each sample.