Answer:
First statement: 10 road workers take 5 days to complete a work, working 2 hours a day.
Let us calculate how many days 2 workers will need, if they were to work at the same pace (i.e. each working 2 hours a day). The workforce is now decreased to 2 divided by 10 = 1/5 (i.e. one-fifth).
Therefore proportionately, the time will increase to 5 days divided by 1/5, (i.e. 5 / (1/5) = 25 days.
We now know that 2 workers will need 25 days to finish the work, if they work for 2 hors a day.
Now the question is what will happen if the two people work 5 hours per day, instead of 2 hours per day?
The labor they put in has increased to 5 divided by 2 = 2.5 (i.e. 2 and half times).
Consequently, the time needed to finish the work will decrease to 25 divided by 2.5 (i.e. ( 25 / 2.5 ) = 10. days.
The answer : 10 Days.