The cost of plastering the four walls of a room is Rs.25. The cost of plastering a room twice in length, breadth and height will be (is Rs.)

Correct option is C

Given: The cost of plastering the four walls of a room is Rs.25. A room twice in length, breadth and height.

Formula used:

Surface Area = $$2 \times (l \times h + b \times h)$$​​

Solution:

The surface area of the four walls of the room,

Surface Area = $$2 \times (l \times h + b \times h)$$​

The surface area of the four walls for the new room,

If length breath and height is twice then,, 2l , 2b and 2h

New Surface Area = 2 × (2l × 2h + 2b × 2h)

=2 × (4 × l × h + 4 × b × h)

= 8×h × (l + b)

​Then cost of plastering the four walls of new room = $$\frac{8 ×h ×(l+ b) \times 25}{2 ×h ×(l+b)}$$​

= Rs. 100

Thus, the correct answer is (c).