Asample initially contains 1.6 moles of a radioactive isotope. how much of the sample remains after four half-lives?

After four half-lives 0.1 mole of the radioactive isotope would remain. If the amount of the isotope that remains after each half life is one half of previously existing amount. Half of 1.6 equals 0.8, half of 0.8 equals 0.4, half of 0.4 equals 0.2, and finally half of 0.2 equals 0.1 mole.

Smooth Paint

Step-by-step explanation:

Glide Paint is the simplest and cheapest: 28.92 per gallon

Smooth Paint is 3 quarts for 22.75. That equates to roughly $7.58333333 per quart. There are 4 quarts in a gallon. So $7.583333333*4 = $30.33 per gallon

One-Coat Paint is 4 pints for $15.00. There are 8 pints in a gallon, so double $15 and you get $30

TL;DR: Glide Paint: $28.92, One-Coat Paint: $30, Smooth Paint: $30.33