Since everyone is working 4 hours a day, and X is the slower person, it was a logical choice to avoid fractions. You could find the answer in terms of hours of X and then divide by 4; the eventual result would be the same! regards J Reply
CAT-holics 
In 4th question how have you reached to 4 hrs worth of work by X?
Since everyone is working 4 hours a day, and X is the slower person, it was a logical choice to avoid fractions. You could find the answer in terms of hours of X and then divide by 4; the eventual result would be the same!
regards
J