The Half-Life of Is 24 Minutes

The half-life of is 24 minutes.A freshly prepared sample is allowed to sit for 2.0 hours.If the mass of the sample after this period of time is 1.0 mg,what was the original sample mass?

A) 0.031 mg
B) 1.3 mg
C) 5.0 mg
D) 32 mg
E) 3.2 × 10² mg