Answer: 11 feet.
Explanation:
Given: A scale model of a boxcar of a train has a length of 10 inches and a width of 2 inches.
The length of the real boxcar = 55 feet.
Let x be the width of the real car.
We know that the corresponding dimension of two similar models are proportional, therefore we have

Hence, the width of the real boxcar is 11 feet.