Assuming the balloon is perfectly spherical and that the 12" you state refers to the diameter of the balloon then it is obviously 6". If you can't assume any of the above then your question cannot be answered.
The volume will be 5723 assuming that the balloon's elasticity makes no difference.
The average PSI (per square inch) of a balloon before it bursts depends on the composition of the balloon in question. If, however, the balloon in question is a common latex balloon bought at any party store, the average PSI is less than 1/4 pound.
Such that there are 12 inches in one foot, there are 12 inch pounds in one foot pound. Therefore, 5 foot pounds is equal to 12 x 5 = 60 inch pounds.
1 cm = 0.3937 inch 1 inch = 2.54 cm
A millimeter, as almost every 12 inch ruler has centimeters and millimeters on the opposite side of where inches are marked.
A circle with a 12 inch diameter has a 6 inch radius.
12 inch
6 inch, because the radius the basically half of the diameter
6 inch
6 inches because the 12-inch softball would be the diameter.
12 inches
12 inch diameter(also 6 inch radius).
6 inches
12"
If you are talking about 9 and 12 inch diameter, then divide both by 2 to get the radius. The area of a circle is pi (3.1415 is good for most calculations) multiplied by the square of the radius. So for the 12 inch circle, the radius is 6. The square of the radius is 36, and multiplying this by pi gives approximately 113.1 square inches. Now the 9 inch circle has a radius of 9/2 or 4.5. Squaring this we get 20.25, which multiplied by pi is approximately 63.6 square inches. If 9 and 12 were already the radius in the problem, just don't divide by 2 since you already have the radius.
I assume 12 is diameter. If so 12/2 is radius of 6in. 6x6xpi is 113.1squared inches
The radius is 6 inches.