Which is the correct calculation for the volume of the prism?

A prism has a length of 8 millimeters, height of 2 and one-half millimeters, and width of 8 and one-half millimeters.

2 and one-half + 8 + 8 and one-half = 19 mm3
2 and one-half times 8 + 8 and one-half = 28.5 mm3
8 times 8 and one-half = 68 mm3
2 and one-half times 8 times 8 and one-half = 170 mm3

The price of a car has been reduced from $19,000 to $11,590. what is the percentage decrease of the price of the car?

Consider the following geometry problems in 3-space enter t or f depending on whether the statement is true or false. (you must enter t or f -- true and false will not work.) f equation editorequation editor 1. a plane and a line either intersect or are parallel t equation editorequation editor 2. two planes parallel to a third plane are parallel f equation editorequation editor 3. two lines either intersect or are parallel f equation editorequation editor 4. two planes orthogonal to a third plane are parallel f equation editorequation editor 5. two planes orthogonal to a line are parallel f equation editorequation editor 6. two planes either intersect or are parallel f equation editorequation editor 7. two lines orthogonal to a third line are parallel t equation editorequation editor 8. two lines parallel to a third line are parallel t equation editorequation editor 9. two planes parallel to a line are parallel f equation editorequation editor 10. two lines parallel to a plane are parallel f equation editorequation editor 11. two lines orthogonal to a plane are parallel

The volume of a spherical hot air balloon v(r) = 4 3 ? r3 changes as its radius changes. the radius is a function of time given by r(t) = 3t. find the instantaneous rate of change of the volume with respect to t at t = 2.