the speed of the boat in a still water is 15km per hour .It goes 30 km upstream and return downstream to the original point in 4 hours 30 minutes.Find the speed of the stream?
Answers
Answer:
25 km/hr
Step-by-step explanation:
Ohkk so.. let the speed of the stream be xkm/hr
so speed of the boat going upstream will be (15-x) km/hr
and speed goin downstream will be= (15+x) km/hr
now 4 hr 30min = 9/2 hr
now we knw that time=distance/speed
so eqn : 9/2 = 30/(15-x) + 30/(15+x)
9/2=450+30x+ 450-30x/(15-x)(15+x)
9/2=900/225-x^2
225-x^2= 900 X 2/9
x^2=225-200
x=+25, -25 km/hr
since speed cnt be negative so speed will be 25km/hr
guys i spent a lot of tym writing this pls mark it brainliest
gud day.
Answer:
The speed of the stream is 15 km/hr.
Step-by-step explanation:
Let the speed of the stream be x km/hr
Given, Distance = 30 km
while going upstream,
Speed of the boat = 15 - x
Hence, Time taken = 30 / 15 - x
While returning downstream,
Speed of the boat = 15 + x
Hence, Time taken = 30 / 15 + x
By condition,
30/15-x + 30/15+x = 9 / 2
=> 30(15+x) + 30(15-x) / (15-x) (15+x) = 9 / 2
=> 450+30x + 450-30x / 225 - x² = 9 / 2
=> 900 / 225 - x² = 9 / 2
=> 9(225 - x²) = 1800 (cross multiplication)
=> 2025 - x² = 1800
=> - x² = 1800 - 2025 = - 225
=> x² = 225 => x = 15 (answer).
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