2h16' = 34/15 hours
4h32' = 68/15 hours
Suppose it takes t hours to do the job working together. If the apprentice takes x hours, then it takes Sumi 3/4 x hours. So, we know that
1/t = 1/x + 1/(3/4 x)
Also, we are told that
(34/15)(1/t) + (68/15)(1/(3/4 x)) = 1
solving those equations together, we get
x = 34/3 = 11h20'
Sumi can wash the windows of an office building in 3/4 the time it takes her apprentice. One day they worked on the building together for 2h 16min , then Sumi continued to work alone. It took 4h 32min more to complete the job. How long would it take her apprentice to wash all the windows?
1 answer