Fluorine-18 Undergoes Positron Emission with a Half-Life of 1

Fluorine-18 undergoes positron emission with a half-life of 1.10 × 10² minutes. If a patient is given a 248 mg dose for a PET scan, how long will it take for the amount of fluorine-18 to drop to 83 mg? (Assume that none of the fluorine is excreted from the body.)

A) 99 minutes
B) 1.7 × 10² minutes
C) 1.3 × 10² minutes
D) 3.0 × 10² minutes
E) 2.1 × 10² minutes