a boat cover certain distance b/w two spots in river taking t1 hrs going downstream and t2 hrs going upstream . what time will be taken by boat to cover same distance in still water?
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Dist.=x
Speed =v
Speed of stream = v1
According to question,
t1=x/(v+v1) =>1/t1 =(v+v1)/x .............Eq1
Similarly
1/t2=(v-v1)/x .....................Eq2
Let T be time in still water.
T=x/v ...............Eq3 [As speed of stream is not there]
Add Eq1 and 2,
1/t1 + 1/t2 =( v+v1)/x +( v-v1)/x
(t1 + t2)/t1 t2 = 2v/x
Taking reciprocal and cross multiplication,
x/v =2 t1 t2/( t1+t2)
From Eq3,
T=2 t1 t2/(t1+t2)
This is the required answer.
Speed =v
Speed of stream = v1
According to question,
t1=x/(v+v1) =>1/t1 =(v+v1)/x .............Eq1
Similarly
1/t2=(v-v1)/x .....................Eq2
Let T be time in still water.
T=x/v ...............Eq3 [As speed of stream is not there]
Add Eq1 and 2,
1/t1 + 1/t2 =( v+v1)/x +( v-v1)/x
(t1 + t2)/t1 t2 = 2v/x
Taking reciprocal and cross multiplication,
x/v =2 t1 t2/( t1+t2)
From Eq3,
T=2 t1 t2/(t1+t2)
This is the required answer.
ArjunR:
Try to do yourself or will not understand........
your answer is not correct
Correct answer pls.....
t1 t2/t1+t2
Can u tell where I went wrong?
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