The length, breadth and height of a room are 15m, 10m, 5m respectively. If the length breadth and height are increased by 10% each then work out the increase of the area of the 5 walls of the room.

Given: The length of the room=15m

The breadth of the room =10m

The height of the room=10m

Percentage increment of the lengths=10%

Tip: if y is increased by x% then the new value of y is =y+

=y()

In the above diagram the walls whose area has to be calculated is shown. ( they are numbered as 1,2,3,4,5)

The total summation of these areas before any change is

=

=300+200+150

=650

The length, breadth, height after increment will be:

length=16.5 m

breadth=11m

height=11m

Therefore, the new sum of the five areas is

=

=363+242+181.5

=786.5

Therefore, the change in the area is

=786.5-650

=136.5

Percentage change is

= 21%