A drain at the bottom of a cylondrical water tank is opened and the height of the water is measured at regular time intervals. The tank is refilled and the process is then repeated. The scatterplot above shows the measured height on the y-axis and time on the x-axis for the trials. Which of the following conclusions can be drawn from the observations in the scatterplot?

Options

A. Water flows out of the drain at a constant rate.
B. The flow rate from the tank decreases as the height of the water in the tank decreases.
C. The drain is inefficinetly designed.
D. The is no relationship between the height of the water in the tank and time.

Answer

B

Explanation

A line of best fit for the scatterplot would show that the measured height of the water decreases over time, but the slope becomes less steep over time, too. The slope, change in height divided by change in time, represents the flow rate of water out of the tank. Since the flow changes as the height of the water changes, (A) is incorrect. Because the slope of the line of best fit becomes less steep as the height of the water decreases, it follows that the flow rate decreases as the height of the water decreases. (B) is correct. (D) is incorrect because the height of the water decreases (through at an even slower rate) as time progresses, so there is a relationship between the height of the water and time. (C ) is incorrect because the data presented doesn't imply anything about the efficiency of the drain design.