Answer:
Option e) 320 s
Explanation:
Here, distance = 3.0 km = 3000 m
The velocity of boat when it is going upstream;
Upstream velocity = velocity of boat in still water - velocity of river flow
So, Upstream velocity 
So,Time to go upstream

The velocity of boat when it is going downstream;
Downstream velocity = velocity of boat in still water + velocity of river flow
So, Downstream velocity 
So,Time to go downstream

So, total time (t) = 
Option E is the correct answer.
This would be true. On Jupiter you would weigh 234 pounds if you were 100 pounds on Earth.
X - rays are highly penetrating electromagnetic radiations that are formed when the cathode rays strikes a dense metal.
It has many characteristics such as :
- travels with the speed of light.
Explanation:
direction of electric field is same as that of force experienced by the test charge
A is the answer you can believe me