Ive been searching on the net and found some good sites but found nothing to help me with these questions. Could you please explain how to get the answer? 1. A spherical water tank has a radius of 15m. If water is pumped in at a rate of 10m3/minute, find how fast the level in the tank is rising when the tank is half full. Use the relationship: (rate of depth increase) x (surface area) = (rate of inflow). 2. A man in a boat is 3km offshore and wishes to go to a point that is 5km from his present position. The man can walk at 4km/h and row at 2km/h. At what point on the shore shoud he land so that he can reach his destination in the shortest possible time? Last one 3. A sector of a circle is tohave an area of 32 square units. What value of the sector angle will give a sector with minimum perimeter? Thanks.