Question

PLEASE HELP FAST!!!!

Answer 1

Answer:

Time = 25/9 hr

Step-by-step explanation:

Let speed of boat in still water is x km/hr

then, speed in downstream equals to "x + 3"km/hr

and speed in upstream equals to "x - 3" km/hr

We also know that time taken to travel 3km in upstream is twice as time taken to travel 4km in downstream.

so,  using time = distance/speed

              3/x- 3   = 2 × (4/x + 3)

                3x + 9 = 8x -24

                    5x = 33

                      x = 33/5 km/hr

Net speed in upstream = 33/5 - 3 = 18/5 km/hr

So, Time taken to travel 10km upstream = distance /speed

                      =  (10 × 5) / 18 = 25/9 hr

Time = 25/9 hr