Estimate how many hours it would take to run (at 10 km/h) non-stop across the u. s. from new york to california. suppose that the distance is about 3000 mi

To answer the question, convert first the distance of 3000 miles to kilometers by the conversion factor 1 mile is 1.61 kilometer.
                               (3000 mi) x (1.61 km / 1 mile) = 4830 km
The time it would take to travel this distance is the quotient of  distance divided by speed. 
                                   time = 4830 km / (10 km / h) = 483 h
Thus, the answer is 483 hours. 

Most of the information's that are given in the question is enough for solving this problem. 
Speed of running = 10 km/h
We already know that
1 mile = 1.60934 kilometer
Then
3000 miles = 4828.032 kilometer
The total distance that needs to be covered = 3000 miles
Then
Number of hours required to cover the distance = 4828.032/10 hours
                                                                            = 482.8 hours
I hope the answer has come to your help.