The Half-Life of a Certain Radioactive Substance Is 36 Years $t=0$

Multiple Choice

The half-life of a certain radioactive substance is 36 years. Suppose that at time $t=0$ , there are $27 \mathrm{~g}$ of the substance. Then after $t$ years, the number of grams of the substance remaining will be $\mathrm{N}(\mathrm{t}) =$ $27(1 / 2) ^{t / 36}$ . How many grams of the substance will remain after 198 years?

A) $0.6 \mathrm{~g}$
B) $0.3 \mathrm{~g}$
C) $0.07 \mathrm{~g}$
D) $0.15 \mathrm{~g}$