A uniform path of width 2m surrounding a pool 20m*16m is to be paved with marbels of side 10cm * 8cm each. if marble cost Rs 5 find the cost of paving the path.

First you have to figure out the area of the pool and the path together:

(20m + 2m) * (16m + 2m) = 22m * 18m = 396m^2

When you now subtract the area of the pool from the whole area, you'll get the area of the path:

396m^2 - (20m * 16m) = 396m^2 - 320m^2 = 76m^2 = > area of the path

Next step is to figure out the area of one tile:

0,1m * 0,08m = 0,08m^2

Last step is to figure out, how many tiles fit in 76m^2:

76m^2 / 0,08m^2 = 950

costs: 950 * Rs 5 = Rs 4750