Question

Compute the surface area (in sq. cm) occupied by the rectangular prism shown in the above diagram.

• A. 390

Answer 1

The correct option is A 390
Given the rectangular prism as shown:

If $l,w,h$ be the length, width and height of the prism respectively.
$\Rightarrow l=15\text{cm};w=5\text{cm};h=6\text{cm}$
If we unfold the rectangular prism, the prism can be observed as:

Here, total surface area of the prsim:
$=\text{Sum of areas of all the rectangles}$
$=2\times (15\times 6+15\times 5+6\times 5)$
$=2\times (90+75+30)$
$=2\times 195=390$ sq. cm