Answer:
The value is

Explanation:
From the question we are told that
The length is

The width is

Generally let assume that (k ft) was turned up on each side hence the remaining width is

Now the capacity is also the volume it can hold which is mathematically represented as



At maximum or minimum

=>

=>

Now to see if the value obtained is positive or negative we differentiate a second time
So

at k = 0,25 ft


since a negative value is obtained then k is the maximum value
converting to inches

