Question
A thief noticed a policeman at a distance of 600 metres.
The thief started running and the policeman chased him. The thief and policeman are running at speeds of 12 km/h and 15 km/h, respectively. Find the time (in minutes) required for the policeman to catch the thief.Solution
Convert speeds to m/s: Thief: 12 km/h =12 × (1000/3600) =10/3 m/s Policeman: 15 km/h = 15 × (1000/3600) = 25/6 m/s Relative speed: 25/6 – 10/3 = 5/6 m/s Time to catch thief: Time = Distance/Relative speed = 600/(5/6) = 720 seconds = 12 minutes
The stream flows at 2 km/h. A boat takes 1 hour more to cover 36 km upstream than it takes to go 40 km downstream. What is the distance the boat can cov...
A boat covers 315 km upstream in 7 hours and 525 km downstream in 7 hours. Find the time taken by the boat to cover 420 km in still water.
The speed of the boat in still water is 10 km/hr and the speed of the stream is 5 km/hr. A boat goes 75 km downstream with its usual speed but at the ti...
The speed of the current is 80% lower than the boat's speed in still water. The boat covers 120 km in still water in 8 hours. How long will it take for ...
The ratio of the speed of boat ‘A’ in still water, the speed of boat ‘B’ in still water and the speed of the current is 8:5:2, respectively. If ...
Sita can row 8 km/hr in still water. If it takes her three times as long to row up a river as it does to row down the same distance, find the speed of t...
- A boat takes 4 hours to travel a distance of '4D' km upstream. However, it covers a distance of (4D + 8) km downstream in just 2 hours. Given that the boat...
A boat’s speed against the stream is 66.67% less than its speed in still water. If it covers 180 km downstream in 4 hours, find the time (in minutes) ...
Ratio of speed of boat in downstream and speed of stream is 7:4, if speed of current is 8 km/hr, then find distance travelled (in km) upstream in 7 hours.
A boat travels 30 km upstream and 45 km downstream in 6 hours. If the speed of the stream is 4 km/h and the boat’s speed in still water is 8 km/h, wha...
Relevant for Exams:
