Question

Please who will solve this I will mark as brainlist and Follow him/her.​

Answer 1

Answer:

average speed formula,

= 2 X v1 X v2 / v1 + v2

v1 = 6.5 + 1.5,

= 8

v2 = 6.5 - 1.5,

= 4

average speed = 2 X 8 X 4 / 8 + 4

= 16/3

= 5.333

makes as brainliest

Answer 2

Answer:

The speed of the boat in still water = 6.5 km/hr

the speed of the stream = 1.5 km/hr

1st the man rows the boat downstream.

In downstream we know that total speed of the boat = speed of boat in still water + speed of the stream.

so the total speed of the boat in downstream=6.5 km/hr + 1.5 km/hr =8 km/hr

Let us consider as the distance covered by the boat in downstream = x km

time taken for cover the distance = x/8 hr

But when he comes back it will upstream for him.

similarly in upstream, we know that,

the total speed of the boat = speed of the boat - speed of the stream.

so the total speed of the boat in upstream=6.5 km/hr - 1.5 km/hr=5 km/hr

When he comes back he has to cover that x km.

so the time taken to came back = x/5 hr.

Av. speed = total distance covered / total time taken

                 = (x+x) / {(x/8) + (x/5)}  km/hr

                 = (2x) / (13x/40)  km/hr

                 = (2x * 40) / (13x)  km/hr

                 = 6(1/40) km/hr (Ans.)

Hope it helps you.