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Answer the following work problem. Report your answer to the nearest tenth of a hour.

Petra can do a certain job in 11 hours. Kris can do the same job in 10 hours. Petra and Kris work together to complete the same job. However, Petra starts working 1 hours after Kris starts to work. How many hours will it take for them to complete the job once Kris starts to work? hours