Question
The downstream speed of a boat is 4 km/hr more than its
upstream speed and the ratio of the speed of the boat in still water to the speed of the stream is 5:2. Find the total time taken by boat to travel 42 km downstream and 30 km upstream?Solution
Let the speed of boat in still water be x km/hr and that of stream be y km/hr. ATQ, ⇒ (x + y) – (x – y) = 4 ⇒ y = 2 km/hr ⇒ x = 2 × 5/2 = 5 km/hr Required time = [42/(5+2)] + [30/(5−2)] = 16 hr
- Two cars, ‘X’ and ‘Y’, started from town ‘M’ and ‘N’ respectively towards each other at the same time. When they crossed paths after 6 hour...
A person starts jogging from park gate 'A' at 6:30 AM at a speed of 8 km/h. Another person starts from the same gate at 8:00 AM, jogging in the same dir...
In a 1200 m race, bike A beats bike B by 100 m. bike B beats bike C by 100 m in a 600 m race. If bike A beats bike C by 30 sec in a 720 m race, then wha...
If a person walks 20% more than of his usual speed, reaches his distance 90 minutes before. If the destination is 459 km away, then the usual speed of a...
Ajay and Vishal left the place ‘X’ with different speeds which are in the ratio 9:5 respectively. Ajay left the place 36 seconds after Vishal. If af...
- Two runners ‘A’ and ‘B’, which were 600 km apart, started running towards each other at the same time and met after 4 hours. If the speed of runner...
A and B are travelling towards each other with a speed of 30 km/hr and 40 km/hr. If they started at same time and A covered 20 km less distance than B b...
A truck covers 376 km at a certain speed in 8 hours. How much time would a car take at an average speed of 13 km/h more than that of the speed of the tr...
Ajay and Vishal left the place ‘X’ with different speeds which are in the ratio 5:3 respectively. Ajay left the place 36 seconds after Vishal. If af...
What is the length of the bridge which a man riding 21 km an hour can cross in 3 min.?
Relevant for Exams:
