If the circumference of the round pool is 29 feet, then the volume of the pool (area times depth) is about 267.7 cubic feet.
50
About 4,490 gallons of water.
About 2,794 gallons of water.
If you fill it to four feet deep, the total is 10,408 gallons of water.
Depends on the depth of the water. If you go to four feet deep the total would be about 13,594 gallons.
It is unlikely that the pool is 48 feet deep but there is no indication as to what units the depth is measured in. Consequently it is not possible to answer the question.
27
40 to 50 feet
About 7,650 gallons.
The capacity of that space is 49.087 cubic feet, or 367.2 gallons. (rounded) We have no way of knowing how much water is in it. For all we know, it may be completely empty.
To fill a round pool that is 18 feet in diameter and 5 feet deep, you would need approximately 14 cubic yards of earth.
cylinder 18 feet diameter x 1.5 feet deep volume = 381 cubic feet