Correct Answer - Option 1 : 64 m

**Given: **

The total cost of ploughing = Rs. 65536

Per meter square cost of ploughing = Rs.16

**Formula Used:**

Area of square = Side × Side

Total cost = Area of field × Per meter square cost

**Calculation:**

The total cost of ploughing = Area of field × Per meter square cost of ploughing

⇒ 65536 = Area of field × 16

⇒ 65536/16 = Area of field

⇒ 4096 m^{2} = Area of field

Area of field = Area of Square

Area of square = (Side)^{2}

⇒ 4096 = (Side)^{2}

⇒ √4096 = side

⇒ 64 m = side

**∴ The side of the square is 64m.**