Problem solving

Question

Tracy can wallpaper 5 rooms in a new house in 30 hours. Together with her trainee she can do the wallpaper of the 5 rooms in 19 hours. How long would it take the trainee working by herself to complete the job?

Answer 1

If Tracy requires 30 hours to complete the job, then in 19 hours she will do 19/30 of the job. If the trainee requires x hours to complete the job, then in 19 hours the trainee will do 19/x of the job. Together the fractions must add up to 1 (the whole job).

 

19/30 + 19/x = 1        multiply by LCD 30x

 

19x + 19(30) = 30x

 

570 = 11x

 

x = 51.82 hours