Question
Pipe A and Pipe B could fill a tank together in 18
hours and 12 hours respectively, while pipe C could empty it in 9 hours. If both inlet pipes are opened together for first 5 hours, then pipe C replaced them. Find the time taken by pipe C to empty the tank filled by pipe A and pipe B together.Solution
Let the capacity of the tank be 36 units. (LCM of 18, 12 and 9)
Efficiency of pipe A = 36/18 = 2 units/hr
Efficiency of pipe B = 36/12 = 3 units/hr
Efficiency of pipe C = 36/9 = –4 units/hr ATQ,
Tank filled by pipe A and B together in 5 hours = (2 + 3) × 5 = 25 units
Required time = 25/4 = 6 (1/4) hr = 6 hr 15 min
- Ravi travels from town X to town Y. At 20 km/h he reaches 4 hours late, but at 50 km/h, he reaches 2 hours early. Find the distance between town X and town...
Train A takes 45 minutes more than train B to travel a distance of 450 km. Due to engine trouble speed of train B falls by a quarter, so it takes 30 min...
Two trains X and Y start at the same time in the opposite direction from two points P and Q and arrive at their destinations 25 and 16 hours respectivel...
The speed of a train is 108 km/hr and it takes 14 seconds to cross a man. Find the time taken by train to cross a platform if the ratio of the length of...
- A woman drove for 5 hours at a constant speed of 60 km/h and then drove another 2 hours at a constant speed of 90 km/h. Find her average speed for the whol...
Rohan and Tanuj move towards Dehradun starting from Delhi at a speed of 30 km/h and 50 km/h respectively. If Tanuj reaches Dehradun 300 minutes earlier ...
During the first 90 km of his trip, 'X' drove at a speed of 60 km/h. In the next 150 km, he increased his speed by 'y%' compared to his initial speed. F...
Driving at (4/5) of his usual speed, a man reaches his destination 36 minutes late. Find the time he normally takes to cover the distance.
There was a race of 2480 meters between P & Q on a circular track of 620 meters. First time they meet during the race after 4 minutes of starting of rac...
A and B are travelling towards each other with a speed of 30 km/hr and 40 km/hr. They started at same time and A covered 25 km less distance than B befo...
