The speed of a motor - boat is that of the current of water

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RRB ASM Exam (Ajmer) 2007 click here to view all questions

The speed of a motor - boat is that of the current of water as 36 : 5.The boat goes along with the current in 5 h 10 min. It will come back in -

A5 h 50 min

B6 h

C6 h 50 min

D12 h 10 min

Nithin K ? Nov 20 '2016 at 19:45

Answer is : 6 h 50 min

Explanation:

Let the speed of the motor boat = 36 kmph and 
speed of current stream= 5 kmph. 
The boat goes along with the current in 5 hours 10 minutes = \(\frac{31}{6} hour\)

First We Need To Calculate upstream and downstream for above condition

Speed downstream = (36x+5x) = 41x kmph
Since distance = speed × time, we have
distance = \(41x \times \frac{31}{6} \) km. ..................(i)

Speed upstream =(36x-5x) = 31x kmph
speed = 31x kmph .........................................(ii)

Hence, time taken to come back 
\(Time = \frac{distance}{speed}\)
\(= \frac{equation (i) }{ equation (ii)}\)
\(= \frac{41x \times \frac{31}{6}}{31x}\)
\(= \frac{41}{6} hours\)

= 6 hours 50 minutes.

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Answer is : 6 h 50 min Explanation: Let the speed of the motor boat = 36 kmph and  speed of current stream= 5 kmph.  The boat goes along with the current in 5 hours 10 minutes = \(\frac{31}{6} hour\) First We Need To Calculate upstream and downstream for above condition Speed downstream = (36x+5x) = 41x kmph Since distance = speed × time, we have distance = \(41x \times \frac{31}{6} \) km. ..................(i) Speed upstream =(36x-5x) = 31x kmph speed = 31x kmph .........................................(ii) Hence, time taken to come back  \(Time = \frac{distance}{speed}\) \(= \frac{equation (i) }{ equation (ii)}\) \(= \frac{41x \times \frac{31}{6}}{31x}\) \(= \frac{41}{6} hours\) = 6 hours 50 minutes. Nithin K ? answered Nov 20 '2016 at 19:45 All Comments

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