Arithmetic

Time, Speed & Distance

Medium

applied

Ram can row a boat in still water at the rate of 6 km/hr. He finds that it takes him twice as long to row upstream of a river as to row downstream of the same river, then the speed of the current of the river is

5 km/hr

4 km/hr

3 km/hr

2 km/hr

✅ Correct Option: 4

Ram's speed in still water = 6 km/hr

Rowing upstream takes twice as long as rowing downstream.

Let the speed of current = $c$ km/hr

Upstream speed = $6 - c$ km/hr (rowing against the current)

Downstream speed = $6 + c$ km/hr (rowing with the current)

For the same distance $d$ km:

Time upstream = $\dfrac{d}{6-c}$

Time downstream = $\dfrac{d}{6+c}$

Given that time upstream = 2 × time downstream:

$\dfrac{d}{6-c} = 2 \times \dfrac{d}{6+c}$

Canceling $d$ from both sides:

$\dfrac{1}{6-c} = \dfrac{2}{6+c}$

Cross multiplying:

$6 + c = 2(6 - c)$

$6 + c = 12 - 2c$

$c + 2c = 12 - 6$

$3c = 6$

$c = 2$

Therefore, the speed of the current is 2 km/hr.

2026: 21 May Shift 2

In a 200 meter race, Taniya beats Geetansh by 40 meters or by 10 seconds. The time taken by Taniya to complete the race will be:

2025: 27 May Shift 1

A swimmer whose speed in swimming pool is 5 km/h, swims between two points in a river and returns back to starting point. He took 20 minutes more to cover the distance upstream than to cover downstream. If the speed of stream is 2 km/h, then the distance between two points is

2026: 18 May Shift 2

Mr. X runs 5 times as fast as Mr. Y. If Mr. X gives Mr. Y a start of 80 meters, how far must the goal on the race course be so that Mr. X and Mr. Y reach it at the same time?

2026: 30 May Shift 2

In a race of 1000 metres, X gives Y a start of 175 m and defeats him by 50 seconds. If speed of X is 5 m/s, then the speed of Y is

2025: 14 May Shift 2

A person can row a boat at 5 km/hr in still water. If the speed of water current in a river is 1 km/hr, and it takes him 1 hour to row to a place and come back, how far off is the place?

2025: 21 May Shift 2

In a 500 m race, the ratio of speeds of two participants, A and B, is 4:5 respectively. If A has a start of 180 m, then the distance by which A wins is

Ram can row a boat in still water at the rate of 6 km/hr. He finds that it takes him twice as long to row upstream of a river as to row downstream of the same river, then the speed of the current of the river is

Solution

Related questions:

Keyboard Shortcuts

CUET Mathematics Past Year Questions (Topic-Wise)