dunkin77 wrote:Hi,
The answer is E) but I am curious what information will be needed to get the answer C)? (how to get "cubic feel per minutes"? )
. What is the rate, in cubic feet per minute, at which water is flowing into a certain rectangular tank?
(1) The height of the water in the tank is increasing at the rate of 2 feet per minute.
(2) The capacity of the tank is 216 cubic feet.
the volume of a rectangular tank is given by breadth * length * height ...
consider a rectangular tank with the dimensions breadth = 10, length = 10 and height =20 (all are in feet)... also consider it to be completely empty...
now, suppose that water starts falling into the tank and consequently the level of water starts increasing ... let the flow of water continue for a minute and then stop,suppose the level of water after a minute is 10 feet .. so this water in the tank at a level of 10 feet also forms a rectangular solid the dimension of which is breadth=10 , length=10 and height =this the level of water after 1 minute= 10 ... therefore, the amount of water after a minute = length*breadth*height = 10*10*10=1000 cubic feet ... that means the rate of water flow is 1000 cubic feet per minute ... so what all do u need to find the rate ? ..we need the length, breadth and the level of water after a minute
now take a look at the 2 statements...
the first statement says that the level of water increases by 2 feet .. which gives us the level (height of the water) but not the length and breadth .. so insufficient
the second statement says volume = 216 ... that is length*breadth*height = 216 .. which again does not give the length, breadth or the level of water so insufficient
similarly combining the 2 also does not give us the value of length, breadth and the level of water ... so the answer is E
