Find the tank capacity (e.g. how many gallons were in the tank on Day 0)

Question

You are using a gas-powered generator to run a motor that uses gas energy at a constant rate regardless of the level in the tank. You have the gas tank filled to maximum capacity on Day 0, and immediately start the generator. At the same time of day, on Day 4 the level in the tank reads 10.2 gallons, and on Day 10, the level in the tank reads 6.6 gallons.

Answer 1

Let x = number of days

     y = number of gallons remaining on day x

 

Since the energy is used at a constant rate, the relationship between x and y is linear.

 

So, (4, 10.2) and (10, 6.6) are 2 points on a line.

 

Slope = (6.6 - 10.2) / (10 - 4) = -0.6

 

Equation of line:  y - 10.2 = -0.6(x - 4)

 

                         y - 10.2 = -0.6x + 2.4

 

                                  y = -0.6x + 12.6

 

Level of tank on day zero is -0.6(0) + 12.6 = 12.6 gal