Question

A boat takes 3 min to travel 1 km downstream and 4 min to travel the samedistance upstream. The speed of the boat in still water and the speed of the waterare
(1) 15 km/h; 5 km/h
(2) 17.5 km/h , 5 km/h
(3) 17.5 km/h , 2.5 km/h
(4) 15 km/h; 2.5 km/h​

Answer 1

Answer:

I think it will help you

Explanation:

Correct option is

C

6 hours 50 min

Let the speed of the motorboat be 36x km/hr and that of the current water be 5x km/hr.

Speed downstream =(36x+5x) km/hr =41x km/hr

Speed upstream =(36x−5x)=31x km/hr

Time taken to downstream =5 hrs 10 min

= 5

60

10

hrs =

6

31

hrs

∴ Distance covered downstream = (41x×

6

31

) km

∴ Distance covered upstream = (41x×

6

31

) km

∴ Time taken to travel upstream = (41x×

6

31

×

31x

1

)hrs=

6

41

hrs=6

6

5

hrs =6 hrs 50 min

Answer 2

Answer:

20kmph. - 15kmph

5kmph is the speed of stream

then speed of boat is 15kmph