Trains Boats and Streams Practice Test 1 with solutions

Question : 8 of 40

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A sailor goes 12 km downstream in 48 minutes and returns in 1 hour 20 minutes. The speed of the sailor in the still water is:

Solution:

Speed downstream a =

D/T

a =

{12}/{{48}/{60}}

{12×60}/{48}

= 15 km
Speed upstream b =

{12}/{1+1/3}

{12}/{4/3}

{12×3}/4

= 9 km
Speed of the sailor in the still water =

1/2 (a+b)

1/2 (15+9)

1/2 × 24

= 12 kmph

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