Question

A box of dimensions 25cm * 30cm * 45cm is to be painted. A container which contains colour has a capacity to paint 1075cm^2. How much containers are required to paint the box completely?

(a) 6

(b) 5

(c) 4

(d) 3

I had been asked this question in exam.

My question is taken from Surface Area of a Cuboid and a Cube topic in section Surface Areas and Volumes of Mathematics – Class 9

Answer 1

The correct option is (a) 6

For explanation I would say: For the box, l = 25, b = 30 and h = 45 (given)

Total surface area of the box = 2(lb + bh + lh)

= 2{(25*30) + (30*45) + (25*45)}

= 2{3225}

= 6450 cm^2.

1075 cm^2 of area can be painted by one container.

Therefore, to paint 6450 cm^2 of area, number of containers requires are = \(\frac{6450}{1075}\) = 6.