Answer
$y=8-\frac{1}{4}t$
$28$ hours
Work Step by Step
Let $x$ be the time in hours and $y$ be the height in feet.
The rate of the receding in feet per hour is:
$$3~\frac{in}{hr}\times\frac{1~ft}{12~in}=\frac{1}{4}~\frac{ft}{hr}$$
The mathematical model will be:
$$y=8-\frac{1}{4}t$$
At $y=1$:
$$1=8-\frac{1}{4}t$$
$$-7=-\frac{1}{4}t$$
$$28=t$$
$$t=28$$
Thus, the time when the flood is $1$ foot above the flood stage is $28$ hours.
