Speed of boat in still water is 9 km/hr. Stream speed initially is 2 km/hr but it increases by 3 km/hr after every hour. Find the time after which boat will come back to the position where it started.(in hour)

At an average of 80 km/hr Shatabdi Express reaches Ranchi from Kolkata in 7 hrs. Then the distance between Kolkata and Ranchi is

The two trains cross each other in 12 seconds, moving in the opposite direction, and they take 60 seconds to travel in the same direction. both trains can have speed in (m/sec).

A man sets out on a journey. He travelled for a total of 16 hours. He covered the first half of the distance at a speed of 40 km / h and the second half at 60 km / h. What is the total distance he travelled?

An office opens at 10 am and closes at 5 pm. The lunch break is of 30 minutes. What is the ratio of lunch break and total office hours?

Two buses travel to a place at 45 km/hr and 60 km/hr respectively. If the second bus takes 5½ hours less than the first for the journey, the length of the journey is:

A train crosses two persons travelling at 3 kmph and 5 kmph in the same direction in 10 seconds and 11 seconds respectively. The speed of the train is:

A train travels the distance between station P and Q at a speed of 126 km/h, while in the opposite direction it comes back at 90 km/h. Another train travels the same distance at the average speed of the first train. The time taken by the second train to travel 525 km is: