Question
Speed of a boat in still water is 9 km/hr. It goes 12 km
downstream and comes back to the starting point in three hours. What is the speed of water in the stream?Solution
Let the speed of the boat = 9km/hr Speed of current = x km/hr Speed upstream = (9 – x) km/hr Speed downstream = (9 + x) km/hr Time upstream + time downstream = 3 hours Time = distance/(speed ) 12/(9-x)+ 12/(9+x) = 3 x = 3 km/hr
A is cycling at an average speed of 24 km/hr such that he can reach a certain point at 12 noon. If he cycles at 36 km/hr, then he will reach the destina...
A cheetah spotted a fox running away at 6 m/s and started chasing it at 10 m/s. The fox was 120 metres ahead at that moment. Find the time taken by the ...
Driving at (4/5) of his usual speed, a man reaches his destination 36 minutes late. Find the time he normally takes to cover the distance.
If the diameter of a sphere is 42 cm, find the total surface area of the sphere.
Two trains for Mumbai leave Delhi at 6 a.m. and 6:30 a.m. and travel at 100 km/h and 136 km/h respectively. Approx. how many km from Delhi will the two ...
βAβ and βBβ started moving towards each other at same time with a speed of 12 km/hr and 16 km/hr, respectively. If the distance covered by βB ...
- Two bikers, βCβ and βDβ, start from point βRβ and βSβ respectively towards each other. They meet after 7 hours, and biker βDβ has trave...
βAβ and βBβ started moving towards each other at same time with a speed of 22 km/hr and 33 km/hr, respectively. If the distance covered by βAοΏ½...
- Bus 'X' and Bus 'Y' start together from a station heading in the same direction. Bus 'X' moves at 18 km/h while Bus 'Y' moves at 30 km/h. Determine the dis...
The ratio of the speeds of Y and Z is 7 : 5. When Y increases his speed by 40%, he covers 294 km in 3 hours. Find the time taken by Z to cover 200 km.
Relevant for Exams:
