Question

At 6:00 a.m., there were 800,000 gallons of water remaining in a reservoir. After 8 hours of irrigation, there were 100,000 gallons of water remaining. Write a linear equation that describes the number of gallons of water remaining as a function of the time the field had been irrigated.

Answer 1

100000x=800000. When the question gives the beginning amount, time passed, and end amount, you always write an equation like this (end amount)x=(starting amount) where x will be the time passed.

Answer 2

WR(t) = 800000 - 87500t

Step-by-step explanation:

t is the time in hours.

WR(t) is the Water Remaining as a function of the time, in gallons.

Answer:

WR(t) = 800000 - 87500t

Step-by-step explanation:

t is the time in hours.

WR(t) is the Water Remaining as a function of the time, in gallons.

Answer:

WR(t) = 800000 - 87500t

Step-by-step explanation:

t is the time in hours.

WR(t) is the Water Remaining as a function of the time, in gallons.

The problem states the initial amount of water in the reservoir is 800000 gallons.

Then we need to find the amount of water spent each hour. For this we know that after 8 hours, 100000 gallons remain.

In other words:

800000 - 100000 = 700000 gallons have been spent in 8 hours.

Which gives a ratio of 700000 / 8 = 87500 gallons per hour.

Writing all together, the linear equation is built by taking the initial amount of water and subtracting the ratio of water spent, multiplied for the time variable:

WR(t) = 800000 - 87500t