There are 3 inlet taps and 1 outlet tap with diameters 8, 6, 2 (cms – inlet taps) and 4 cm respectively. The rate of flow of oil is directly proportional to the square of the radius of the tap. It takes 9 minutes for the smallest tap to fill an empty tank. What is the time taken to fill an empty tank when all the taps (inlet + outlet) are kept open?

Question

anonymous · Answer

the answer is similar to this http://wiki.answers.com/Q/How_much_time_is_required_to_fill_a_tank_if_pipe_A_can_fill_it_in_20_minutes_pipe_B_can_fill_it_in_30_minutes_and_pipe_C_can_drain_it_in_40_minutes_and_all_of_the_pipes_are_opened_on_an_empty_tank

anonymous · Answer

shoot i just answered this and lost it somehow!!  i've no time to type it now = the answer i got was 9/22 minutes

anonymous · Answer

scroll down for related answers in the link I provided. You should get an idea as to how to approach this problem

anonymous · Answer

could you help how to calcuate the rate of flow

anonymous · Answer

rate of flow is proportional to radius squared
so flow rate of tap A = k*8^2 = 64k
similarly the flow rates of the other three are 36k, 4k and 16k

anonymous · Answer

Hi, but shouldn't the radius be 4, since diameter is 8

anonymous · Answer

oh you are right. well spotted.
so it is 16k, 9k, k and 4k

anonymous · Answer

getting the answer as 18/22, but it seems to be 7/22

anonymous · Answer

total flow = 26-4= 22

anonymous · Answer

hi

anonymous · Answer

total flow rate is 22k per minute. so what is the next step?
what is the value of k?

anonymous · Answer

total capacity of the tank is 36 units (2^2*4.5)

anonymous · Answer

total flow that comes is 16+9+1-4==22

anonymous · Answer

ok got it, total 9 units, 9/22

anonymous · Answer

thanks for your help

anonymous · Answer

np. glad you could work it out on your own.