A wet porous subtance in the open air loses its moisture at a rate proportional to the moisture content. If a sheet hung in the wind loses half its moisture during the first hour, then the time when it would have lost 99.9% of its moisture is (wether conditions remaining same)

A wet porous substance in the open air loses its moisture at a rate proportional to the moisture content. If a sheet hung in the wind loses half its moisture during the first hour, when will it have lost 95% moisture, weather conditions remaining the same?

A wet porous substance in the open air loses its moisture at a rate proportional to the moisture content. If a sheet hung in the wind loses half its moisture during the first hour, when will it have lost 90% , weather conditions remaining the same?

A certain radioactive material is known to decay at a rate proportional to the amount present. If initially there is 50 kg of the material present and after two hours it is observed that the material has lost 10% of its original mass, find () and expression for the mass of the material remaining at any time t, (ii) the mass of the material after four hours and (iii) the time at which the material has decayed to one half of its initial mass.

Progressive express left for New Delhi increasing its speed in each hour. Its started its journey from lucknow, but after four hours of its journey it met with accident its speed in the fourth hour was 7/5 times that of the third hour and the speed in the third hour was 10/7 times that of the second hour and in the second hour it was 7/5 times that of the first hour. if it would have been travelled with the half of the speed that of the third hour, then it would have gone 160 km less in the same time . The average speed of the train during the journey of 4 hours was: