I assume the solid is a "regular hexagonal prism", by which it means that the cross section is a regular hexagon with all sides and angles equal.
Also, the exact apothem is 9.5262... but we will adopt the given value of 9.5.
First lateral surface area
A1=6*side length*height=6*11*20=1320 units
Then the end areas
A2=2 faces * 6 triangles/face * [base * height (apothem) /2]
=2*6*11*9.5/2
=627 units
Total area=1320+627=1947 units
