Question

The cost of white-washing the four walls of a room is $Rs.20000$. The cost of white-washing a room twice in length, breadth and height will be-

• A. $Rs.40000$
• B. $Rs.60000$
• C. $Rs.80000$
• D. $Rs.100000$

Answer 1

The correct option is C $Rs.80000$

Here area of four walls$=2(l+b)\times h=A$
According to the question
$=2[2l+2b]\times 2h$
$=2\times 2\times 2[l\times b]\times h$
$=4\times \left[2\right(l+b)\times h]$
$=4\times A$
$=4A$
As area will be four times, therefore cost will be four times.