By the tenth repetition trainees must be able to complete the assembly task in 1 hour or less. Susan sweaney has just spent 7 hours on the fourth unit and 5 hours completing her eighth unit, while another trainee, Julie Burgmeier, took 4 hours on the third and 3 hours on the sixth unit.
Time required by Susan for the tenth unit? (Must round all intermediate calculations to at least three decimal places before proceeding with subsequent calculations)
Hours ___