Officer Aptitude Rating (OAR) Practice Test

To determine how long it will take to fill the tank when both pipes are open, we should first ascertain the filling and draining rates of the respective pipes. The filling pipe can fill the tank in 25 minutes. This means it can fill 1/25 of the tank's volume per minute. Conversely, the draining pipe empties the tank in 50 minutes, equating to a rate of 1/50 of the tank's volume per minute. When both pipes are open simultaneously, the net rate of filling the tank is derived by subtracting the draining rate from the filling rate. Hence, we have: Filling rate: 1/25 tanks per minute Draining rate: 1/50 tanks per minute To combine these rates effectively, we find a common denominator. For 25 and 50, the lowest common multiple is 50: - The filling rate becomes 2/50 tanks per minute (since 1/25 = 2/50). - The draining rate remains 1/50 tanks per minute. Now, we can subtract the draining rate from the filling rate: Net Rate = (2/50) - (1/50) = 1/50 tanks per minute. Therefore,