To find out how long it takes the man to cover one mile, we first need to convert the time he takes to run 20 miles into a more manageable format.
One hour and forty minutes can be converted to minutes:
- 1 hour = 60 minutes
- 40 minutes = 40 minutes
So, the total time is: 60 minutes + 40 minutes = 100 minutes
Now, if he runs 20 miles in 100 minutes, we can calculate the time to run one mile by dividing the total time by the total distance:
\[ \text{Time per mile} = \frac{\text{Total time}}{\text{Total distance}} = \frac{100 \text{ minutes}}{20 \text{ miles}} = 5 \text{ minutes per mile} \]
Thus, it takes him 5 minutes to cover one mile.