Answer
Find out the how far above the water surface is the top of the pipe .
To prove
As given
A pipe that is 3.1 meters long is placed vertically in a pond.
Its lowest point is 1.5 meters under the water surface.
thus
The top of the pipe far above the water surface = 3.1 - 1.5
= 1.6 meter
Therefore the top of the pipe far above the water surface is 1.6 meter .
