Final answer:
The mass of the box is 12.94 kg.
Step-by-step explanation:
To find the mass of the box, we can use Newton's second law of motion, which states that force is equal to mass times acceleration (F = ma). In this case, the force applied by the fisherman is 44.0 N and the acceleration of the box is 3.40 m/s².
Using the formula F = ma, we can rearrange it to solve for mass: m = F/a. Plugging in the values, we get m = 44.0 N / 3.40 m/s² = 12.94 kg.