A boat covers x km downstream in 6 hours and also covers the same distance upstream in 15 hours. If the speed of the stream is decreased by 20%, then the time taken by the boat to cover 235 km downstream is 5 hours. Find the value of x?<\/p>
A. 210<\/p>
B. 300<\/b><\/p>
C. 160<\/p>
D. 100<\/p>
E. None of these<\/p>
Sol:<\/p>
Speed of the boat=y <\/p>
Speed of the stream=z <\/p>
x\/(y+z)=6 <\/p>
x\/(y-z)=15 <\/p>
6y+6z=15y-15z<\/p>
9y=21z <\/p>
y=7z\/3 <\/p>
235\/(7z\/3+z*4\/5)=5 <\/p>
705=47z <\/p>
z=15 <\/p>
Speed of the stream=15 kmph <\/p>
Speed of the boat=35 kmph <\/p>
x\/(y+z)=6 <\/p>
x\/(35+15)=6<\/p>
x=300 km<\/p> <\/p>\n","protected":false},"excerpt":{"rendered":"
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