The length and breadth of a hall are in the ratio 4: 3 and its height is 5.5 meters.

Let the length be 4a and breadth be 3a

Height = 5.5m [Given]

As mentioned in the question, the cost of decorating 4 walls at the rate of Rs. 6.60 per m² is Rs. 5082.

Area of four walls * rate = Total cost of Painting

2(l + b) * h * 6.6 = 5082

2(4a + 3a) * 5.5 * 6.6 = 5082

$7 a=\frac{5082}{2 * 5.5 * 6.6}$

7a = 70

a = 70/7

a = 10

Length = 4a = 4*10 = 40 m

Breadth = 3a = 3*10 = 30 m