Subject
Quantitative Aptitude
Topic
Speed & Distance
Two boats are 50 km apart from each other in the direction of the flow of river. The speed of each boat in still water is 20 km/hr. They both start moving towards each other at same point of time. After how much time will they meet? (Assume that the river is straight and has no turns)
Two boats are 50 km apart from each other in the direction of the flow of river. The speed of each boat in still water is 20 km/hr. They both start moving towards each other at same point of time. After how much time will they meet? (Assume that the river is straight and has no turns)
ক)
1 hourখ)
1 hour and 15 minutesগ)
1 hour and 30 minutesঘ)
2 hoursঙ)
Cannot be determinedExplanation
Speed of each boat in still water = 20 km/hr Suppose the speed of stream is v km/hr. ⇒ Speed of boat that goes upstream = (20 – v) km/hr And, Speed of boat that goes downstream = (20+v) km/hr Suppose the boats meet after T hours. We know, Distance = Speed × Time ⇒Distance covered by boat moving upstream = (20-v) km/hr × T hr = (20-v)T km ⇒Distance covered by boat moving downstream = (20+v) km/hr × T hr = (20+v)T km Now, total distance covered by boats should be equal to 50 km. ⇒ (20 – v)T + (20+v)T = 50 ⇒ 40T = 50 ⇒ T = 1.25 hours = 1 hour + (0.25 × 60 minutes) = 1 hour and 15 minutes ∴Time taken for the boats to meet = 1 hour and 15 minutesRelated questions
A man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is:Speed of a boat in standing water is 9 kmph and the speed of the stream is 5 kmph. A man rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by him is:two trains are moving in opposite directions at 60 km/hr and 90 km/hr. Their lengths are 1/10 km and 9 km respectively. The time taken by slower train to cross the faster train in seconds is -A man can row three-quarters of a kilometre against the stream in 11×(1/4) minutes and down the stream in 7×(1/2) minutes. The speed (in km/hr) of the man in still water is:In a 300 m race A beats B by 5 metre or 6 seconds. B's time over the course is -A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?A boat covers a certain distance downstream in 1 hour, while it comes back in 1x(1/2) hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?A man buys tk 20 shares paying 9% dividend. The man wants to have an interest of 12% on his money. The market value of each share is-