Let the dimension of the rectangular lot be

*x* and

*y**x* = sides parallel to water

*y* = sides perpendicular to water

Perimeter

$2x + 2y = 1000$

$x + y = 500$ ← Eq. (1)

Cost of fence

$25x + 5(2y) = 9500$

$5x + 2y = 1900$ ← Eq. (2)

Equation 2 - 2 × Equation (1)

$3x = 900$

$x = 300 ~ \text{ft}$

From Equation (1)

$300 + y = 500$

$y = 200 ~ \text{ft}$

Answer = 300 ft × 200 ft → [ D ]