polystyrene has dielectric constant 2.6 and dielectric strength 2.0 × 107 v/m. a piece of polystyrene is used as a dielectric in a parallel-plate capacitor, filling the volume between the plates.

would be false hope this out

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form