A boat covers a certain distance downstream in 8 hours and comes back upstream in 10 hours. If the speed of the current be 1 km/hr the distance (in km) of the one way journey is
Answers
Answer:
Let us take the speed of the boat as v km/h.
One must keep in mind that while travelling downstream, total speed
= speed of boat + speed of current = v+1 km/h
While travelling upstream, the boat travels against the current( always ), therefore, total speed= v- 1 km/h
The distance travelled in both cases is given as the same. Let us take it as x km.
Therefore, using the basic equation of motion,
distance= speed × time
we have two cases.
Case I-
x= (v+1)× 8 ( since greater speed means lesser time taken )
Case II-
x= (v-1) × 10
Equating the two, we get-
(v+1) 8= (v-1) 10
⇒ 8v + 8= 10v - 10
⇒ 2v= 18
⇒ v= 9 km/h
Now distance can be calculated by substituting 'v' in either of our two cases.
x= (v+1) 8
⇒x= ( 9+1) 8
⇒x = 10 × 8
⇒x = 80 km
Answer:
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