Mario walked at 3.9 miles per hour for 0.72 hours how far did she walk

The speed at which Mario can walk is given in the question and it is 3.9 miles/hour. Also we get to know from the question that Mario walked for 0.72 hours. The question requires the answer to the distance for which Mario walked.
Now
Mario in 1 hour can cover a distance of 3.9 miles
The n
The distance covered by Mario in 0.72 hours = (3.9 * 0.72) miles
                                                                         = 2.808 miles
Then the distance covered by mario in o.72 hours is 2.808 miles.

No solution : there is no number of boxes that she bought