AbdurRakib wrote:
How many hours would it take Pump A and Pump B working together,each at its own constant rate,to empty a tank that was initially full?
(1) Working alone at its constant rate,Pump A would empty the full tank in 4 hours 20 minutes.
(2) Working alone,Pump B would empty the full tank at its constant rate of 72 liters per minute.
OG Q 2017 New Question(Book Question: 186)
(1) Working alone at its constant rate,Pump A would empty the full tank in 4 hours 20 minutes.
A will empty the tank in 260 minutes.
Rate of A * 260min= VOLUME TO BE EMPTIED
We don't know the rate of A or volume of the tank
INSUFFICIENT
(2) Working alone,Pump B would empty the full tank at its constant rate of 72 liters per minute.
B's rate is 72 litre per minute.
72*time = volume
We don't know volume of the tank so or how much time B takes to empty.
INSUFFICIENT
Combining 1 and 2, we still don't know the total water in the tank
rate of A*260 = 72*time of B
Even if we change rate into time or time into rate, we will still have two unknowns {volume and time} or {volume or rate}
{V and R } or {V and T}
Obvious enough we still cannot solve this equation because we do not know the volume
INSUFFICIENT
ANSWER IS E
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