Question

The ratio between the sides of a room is 5 is to 3. The cost of whitewashing the ceiling of a room at 50 paise per square metre is rupees 270 and the cost of papering the walls at 10 paise per square metre is rupees 48. The height of the room is​

Answer 1

Area of the ceiling

=

Costof1sq.unit

Totalcost

=

0.50.

Rs.270

=540

l:b=5:3 or l=5x and b=3x

so that, 5x×3x=540m

2

⇒x

2

=36m

2

or x=6m

∴ l=30m; b=18m

Area of the four walls

=

Costof1sq.unit

Totalcost

∴Height=

2(l+b)

Areaoffourwalls

=

2(30+18)

480

=5m