Question

22. Bob and James are finishing the roof of a house. Working alone, Bob can shingle the roof in 10 hours. James can shingle the same roof in 16 hours. How long will it take them working together to shingle the roof? Round your answer to the nearest hundredth if necessary


I don’t understand this

Answer 1

look at how much of the job each can do in 1 hour
Bob does 1/10 of the job
James does 1/16 of the job.
Together, they can do 1/10 + 1/16 = 13/80 of the roof in one hour
So, it will take them 80/13 = 6 2/13 hours

This is why the solution to such work problems is usually written

1/10 + 1/16 = 1/x

Answer 2

26.67 hours i think

Answer 3

Wait... no it's 6.15 hours

Answer 4

6.15 hours trust