Answer:
The depth of snow at 9:00 am was 19 inches.
Step-by-step explanation:
Consider the provided information.
Let x represents the number of hours and S(x) represents the depth of snow.
There was no snow on the ground when it started falling at midnight at a constant rate of 1.5 inches per.
That means the depth of snow will be:

At 4:00 a.m., it starting falling at a constant rate of 3 inches per hour,

7:00 a.m. to 9:00 a.m., snow was falling at a constant rate of 2 inches per hour.

The required piece-wise linear function is

We need to find the how deep was the snow at 9:00 am
For 9:00 am we will choose the function which can take the value of x=9
Substitute the value of x=9 in
Hence, the depth of snow at 9:00 am was 19 inches.