Rosalie exercises for 2/5 of an hour every morning. How much time does she spend exercising in a week?
To find how much time Rosalie spends exercising in a week, we multiply the amount of time she exercises in a day by the number of days in a week.
The amount of time Rosalie exercises in a day is 2/5 of an hour.
The number of days in a week is 7.
So, the total time Rosalie spends exercising in a week is (2/5) * 7 = 2.8 hours. Answer: \boxed{2.8}.