John is arguing that they should use the following expressions to calculate the final cost of this item: (20-20•0.15)+(20-20•0.15)•0.05.

The half-life of a certain material is 0.002 second. approximately how much of a 14-gram sample will be left after 0.004 second? a. 12 grams b. 3.5 grams c. 0.06 gram d. 7 grams