If 250mg of a radioactive element decays to 200mg in 48 hours, find the half-life of the element.

Question

ln(N_o/N) = kt
N_o=250 mg
N = 200 mg
t = 48 hours.
Solve for k, then put k into the following equation and solve for t_1/2.

k = 0.693/t_1/2