Aptitude - Boats and Streams - Discussion

Discussion Forum : Boats and Streams - General Questions (Q.No. 7)
7.
The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is:
1.2 km
1.8 km
2.4 km
3.6 km
Answer: Option
Explanation:

Speed downstream = (15 + 3) kmph = 18 kmph.

Distance travelled = 18 x 12 km = 3.6 km.
60

Video Explanation: https://youtu.be/IDOwWUeOldQ

Discussion:
21 comments Page 1 of 3.

Kanchan Tarwani said:   2 decades ago
why we add current rate with speed of still water??

Brajendra said:   2 decades ago
why we add current rate with speed of still water??it has to
substract

Nagarjun said:   1 decade ago
They have specified as downstream so we have to add.

Sanjana said:   1 decade ago
Why we add current rate with speed?

Bindu said:   1 decade ago
Rate of current=1/2(downstream speed- upstream speed)
ie=1/2[(U+V)-(U-V)]
=1/2(U+V-U+V)
=2V/2
=V
SO RATE OF CURRENT = V(SPEED OF STREAM)

Angu said:   1 decade ago
Thanks bindu

Gautam said:   1 decade ago
Use the formula= if the speed of a boat in still water is U km/hr and the speed of the stream is V km/hr, then

speed down stream = (u+v)km/hr
(15+3)km/hr = 18 km/hr

Distance travelled = (18 x 12/60)=3.6km ANSWER
[60 is here because 1 minute=60seconds]

Kavya mareedu said:   1 decade ago
Thanks goutham.

Debasis said:   1 decade ago
How to calculate distance traveled = (18*12/60)?

NANDINI said:   1 decade ago
12/60 = 0.2.
18*0.2 = 3.6.


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