Final answer:
The student's question involves calculations based on fluid dynamics, where a decrease in water flow rate due to increased usage suggests a corresponding reduction in water pressure, provided the resistance remains constant.
Step-by-step explanation:
To answer the student's question regarding the change in water pressure and flow rate, we use principles from fluid dynamics. Given the initial pressure in a water main, the flow rate through a garden hose can change depending on the pressure supplied to the house. For example, if the initial flow rate was 20.0 L/min at a pressure of 3.00 × 105 N/m2, and later the flow rate drops to 8.00 L/min, we can infer a change in the supplied pressure.
Assuming the resistance in the hose remains constant, this reduction in flow rate indicates a corresponding reduction in pressure. Using the relationship between flow rate and pressure (assuming laminar flow and a constant resistance), which is directly proportional as per Bernoulli's equation, we can calculate the new pressure. Knowing the original flow rate of the water main and the new flow rate can also give us information about the additional users of the water supply, since a higher total flow rate would mean more users are consuming the water.