Question

Cobalt-60, with a half-life of 5.3 years, has a number of

applications, including medical therapy and the sterilization

of medical tools. Determine the mass of a 50 g sample that

would remain after

(a) 6 months

(b) 5 years

Answer 1

$N=N_0(\frac{1}{2})^{\frac{t}{t_{1/2}}}$

a)

$N=50\ g\times(\frac{1}{2})^{\frac{0.5\ years}{5.3\ years}}=47\ g$

Answer: 47 g

b)

$N=50\ g\times(\frac{1}{2})^{\frac{5\ years}{5.3\ years}}=26\ g$

Answer: 26 g