Question

Raju wants to paint a cuboidal box which is 20 cm in length , 15 cm in breadth and 6 cm in depth. Find the area to be painted if the box is open at the top.​

Answer 1

Answer:

1500 $cm^{3}$

Step-by-step explanation:

Total Area=Breadth x Length x Height/Depth

Area=15 x 20 x 6

Area=1800

Area of top= Breadth x Length

                   = 15 x 20

                   = 300

Area to be painted= 1800-300

                                = 1500 $cm^{3}$

Answer 2

Answer:

720 cm^2

Step-by-step explanation:

The box is open at top, so only 5 sides are to be painted.

Let the length be l, breadth be b, and depth be d.

So, total surface area = 2ld + 2bd + lb (as one side is not there, which is the            

                                                                top one with dimensions l and b)

                                   = 2*20*6 + 2*15*6 + 20*15 = 240 + 180 + 300 = 720 cm^2

Note:- This is only when the outer surface is painted. f the inner surface is also painted, then the total surface area = 2*720 = 1440 cm^2.