A boat leaves it's dock and travels upstream at a speed of 40 km/hr and then returns to the dock. What is the speed of the stream if they average speed of the entire trip is 60 km/hr?
none of these
Speed of stream = x. Speed of boat = b. Given, b - x = 40. Also, 2[(b+x)(b−x)](b+x+b−x)=60⇒2(b+x)(40)2b=60. Solving we get b= 2x. 2x - x = 40 , x = 40 (d).
Ankit drives 120 km at 60 km/hr and the next 120 km at 40 km/hr. His average speed during the entire trip is:
A car travels from A to B at a speed of 20 km/hr and returns at a speed of 30 km/hr. The average speed of the car for the whole journey is
A train travels from Station A to Station B covering 200 km and returns to Station A in 10 hours. The speed and the velocity of the train are _____ and _____, respectively.
a) A train travels a distance with a speed of 40 km/h and returns with a speed of 60 km/h. Calculate the average speed of the train.
b) On a 60 km track, a train travels the first 30 km at a uniform speed of 30 km/h. How fast must a train travel the next 30 km so that the average speed is 40 km/hr for the entire trip?
A motorboat travels 30 km downstream in 3 hours and 40 km upstream in 5 hours. Find the speed of the boat (in km/hr).