In Still Water, Peters Boat Goes 4 Times as Fast as the Current of the River. He Took a Trip 15 Miles Up the River, Then Came Back. His Entire Trip Lasted 4 Hours. Find the Rate of the Rivers Current.

2 km/h

Step-by-step explanation:

Let

Rate of river current = x km/h

Speed of Peter's boat = 4x km/h

He takes 15 km trip up (opposite direction)

His speed upstream = 4x - x

= 3x

His speed is 3x and distance is 15 km

Time = Distance / Speed

15/3x

= 5/x

And

Moving downstream (same direction)

Speed will be 4x + x = 5x

Distance = 15km,

speed = 5x

Time = Distance / Speed

= 15/5x

= 3/x

Total time take for trip = 4 hours

Total time take for trip = upstream + downstream

4 =5/x + 3/x

4 = 8/x

Cross product

4 * x = 8

x = 8/4

x = 2

Rate of river current = x km/h

= 2 km/h

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