Length of the rectangular garden = 40 m

Area of the rectangular garden = 1000 sq. m.

∴ length × breadth = 1000

∴ 40 × breadth = 1000

∴ breadth = 1000/40

= 25 m

Now, perimeter of the rectangular garden = 2 × (length + breadth)

= 2 (40 + 25)

= 2 × 65

= 130 m

Length of one round of fence = circumference of garden – width of the entrance

= 130 – 4

= 126 m

∴ Total length of fencing = length of one round of wire × number of rounds

= 126 × 3

= 378 m

∴ Total cost of fencing = Total length of fencing × cost per metre of fencing

= 378 × 250

= 94500

∴ The cost of fencing the garden is Rs 94500