If 75 feet is the circumference of the pond then its radius works out as 12 feet rounded to the nearest whole number and its surface area is pi*12^2 which is 144*pi square feet.
The answer depends on what characteristic you want to measure: its temperature, refractive index, circumference, depth, volume, etc.
9 Acres = 36,421.7 square meters. 4 feet = 1.2 meters. Area x length = volume; 36,421.7 x 1.2 = 43,706 cubic meters. Cubic meters is a volume, which can be converted to liters, 1 cubic meter is 1000 liters. So your pond has 43,706,000 Liters. 1 gallon is 3.78 liters, so divide by 3.78 and your pond has 11,545,903.7 Gallons.
$1,850
Volume = (surface area) x (depth) = 217,800 cubic feet = 1,629,257.1 gallons (rounded)
The area of Thompson Pond is 303,514.23168 square meters.
The area of Watchaug Pond is 2,318,848.7300352002 square meters.
The area of Sunfish Pond is 178,061.6825856 square meters.
The area of Houghton's Pond is 97,124.5541376 square meters.
The area of Trustom Pond is 728,434.156032 square meters.
The area of Alcona Dam Pond is 4,079,231.2737792004 square meters.
The area of Halfway Pond - Massachusetts - is 938,870.6899968 square meters.
The area of Franklin Falls Pond is 1,776,569.9694336 square meters.
The area of Alley Pond Park is 2,651,880.7324601854 square meters.
The area of Little South Pond is 250,905.0981888 square meters.
The area of Black Pond Wildlife Management Area is 2,128,646.4781824 square meters.
Walden Pond in Massachusetts has an area of approximately 61 acres.