A boat travels in upstream. If the speed of boat in upstream in decreased by 40% then it is equal to the speed
of current and speed of boat in still water is given as 240 km/hr. Then find upstream speed of boat? (in km/hr).
1. 120
2. 180
3. 150
4. 210
5. 125
.
Answers
speed of boat in still water=240km/h
speed of stream =x
speed of upstream =(240-x)km/h
given x=60%of(240-x)
x=60(240-x)÷100
100x=14400-60x
160x=14400
x=90
upstream speed =(240-90)km/h
upstream speed=150km/h
Answer:
The upstream speed of the boat is 150 kmph
Step-by-step explanation:
Assumption,
Let the speed of the boat in upstream be 'u'.
Let the speed of the current be 'x'
Given,
The upstream of the boat decreased by 40% = the speed of the current.
i.e. u - (40% of u) = x..(1)
The speed of the boat in still water (v) is 240 km/hr.
To find,
The speed of the boat in upstream (u).
Calculation,
By solving equation (1):
u - (0.4u) = x
⇒ 0.6u = x
Now we know that:
The speed of the boat in still water (v) - the speed of the current 'x' = The speed of the boat in upstream (u).
⇒ v - x = u
⇒ 240 - 0.6u = u
⇒ 240 = 1.6u
⇒ u = 150 km/hr
Therefore, the upstream speed of the boat is 150 kmph.
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