MATHEMATICS · Single correct · AP · Calculus AB · Differential Equations · Differential Equations
Problem
A radioactive sample has an initial mass of 120g. Five hours later, the mass is 80g. Assuming the mass M(t) (in grams) decays at a rate proportional to the amount present, approximately how many additional hours (beyond the initial 5 hours) will pass before the mass decreases to 50g?
(a) 3.8h
(b) 5.8h
(c) 10.8h
(d) 8.1h