6. The Yupi Diliman Chancellor wants to know the current condition of the laboratory rooms in the campus. He tasked an office to determine the total number of laboratory rooms in need of repair. By...

6. The Yupi Diliman Chancellor wants to know the current condition of the laboratory rooms in the campus. He tasked an office to determine the total number of laboratory rooms in need of repair. By drawing lots, ten buildings were randomly selected and all laboratory rooms in each selected building were inspected.

The sampling method used in selecting buildings is ______ sampling.