The length of a cold storage is 5 times its breadth, and its height is 8 m. The area of its four walls (including the doors) is 720 cm². Find the total surface area of cold storage.

1282.5 m²

We know that,

TSA of cuboid = 2(lb + bh + lh) 

We have,

The length of cold storage = 5 times its breadth,

Height = 8 m

The area of its four walls = 720 m² (Doors included)

So,

= l = 5b, h = 8

= Area of four walls = 2(lh) + 2(bh)

= 720 = 2(5b × 8) + 2(b × 8)

= 720 = 80b + 16b

= 720 = 96b

= b = 7.5 m,

l = 5b = 5 × 7.5 = 37.5 m

TSA = 2(lb + bh + lh) = 2(37.5 × 7.5 + 7.5 × 8 + 8 × 37.5)

= 2(281.25 + 60 + 300) = 2(641.25) = 1282.5