Graphing:

A water tank initially (at time t=0min)contains 800 gallons of water. A spigot is opened at the bottom of the tank and water pours out at a constantrate of 40 gallons per minute. Assume that the relation between the volume V of water in the tank and time t is linear.

a) Set up a coordinate system, placing the time t on the horizontal axis and the volume of water V on the vertical axis. Label and scale each axis. Include units in your labels.

b) Use the initial volume of water in the tank and the rate at which the volume of water is decreasing to draw the line representing the volume V

of water in the tank at time t. Use the slope-intercept form to determine the equation of the line.

c) Replace x and y in the equation found in part (b) with t and V, Respectively. Use the result to predict how much time must pass until the water tank is empty.