Could you see, practically without calculation, that the answer in Prob. 27 must lie between 60 and 70 min? Explain.

Data from Prob 27
If a wet sheet in a dryer loses its moisture at a rate proportional to its moisture content, and if it loses half of its moisture during the first 10 min of drying, when will it be practically dry, say, when will it have lost 99% of its moisture? First guess, then calculate.