How many sprinklers should be tested in a representative sample if the total number of sprinklers is 100?

• A. 1
• B. 4
• C. 10
• D. 20

Answer: (C)

Testing a representative sample means selecting a portion of the total sprinklers that can reflect the condition of the whole system. For a total of 100 sprinklers, testing ten gives a 10% sample, which is a practical balance between confidence in the system and the effort required to perform the tests. This size allows you to observe different installation zones and conditions, increasing the likelihood that issues would be detected across the system. Choosing too small a sample, like one or four sprinklers, risks missing problems that aren’t distributed evenly. A larger sample, such as twenty sprinklers, would still be valid but adds testing workload with diminishing returns for standard sampling practices. Therefore, ten sprinklers is the best representative sample here.