Answer:
120 feet
Step-by-step explanation:
Given that the submarine started at the surface of the water and collected data at three different depths.
As each time the submarine dove 40 feet down, so,
the depth covered in one dive = 40 feet.
From the surface, the depth covered in 1 drive, [tex]d_1= 40[/tex] feet
Similarly, the total depth covered in 2 drive, [tex]d_2 = 2\times 40= 80[/tex] feet.
So, for any integer [tex]n[/tex], the depth covered in [tex]n[/tex] drive,
[tex]d_n=40n[/tex]
This is the required integer equation to model the situation.
Since, for three different depths, there must be 3 drive and the submarine will be at the lowest depth after 3rd dive.
So, for the lowest depth, n=3
Hence, the lowest depth = 40x3= 120 feet.