Vanessa C.
asked • 10/27/18Rational expressions
A boat is traveling in a river that is flowing downstream at a speed of 5 kilometers per hour. The boat can travel 30 kilometers upstream in the same time it would take to travel 40 kilometers downstream. What is the speed of the boat in still water?
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1 Expert Answer
Raymond B. answered • 01/16/26
Tutor
5
(2)
Math, microeconomics or criminal justice
current c = 5 kph
b + c = 40/t
b-c = 30/t
add the two equations to get
2b = 70/t
b = 35/t =35 kph if t = 1 hour
= 7 kph if t = 5 hour
= seemingly 1 kph if t = 35 hours but the boat can't move upstream if its speed is = or less than the current speed
it all depends on t
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Sonaal G.
Let's say the speed of the boat in still water is Sb, while the speed of the water stream is Ss. Therefore , Sb + Ss = 5 (since flowing downstream) ------- 1 Also, time = distance/speed. Therefore, 30/(Sb-Ss) = 40/(Sb+Ss) Solving this you get, Sb = 7Ss ------- 2 Solving equations 1 and 2 you get : Sb = 35/8 km/hr and Ss = 5/8 km/hr10/27/18