Question

The amount of a radioactive substance remaining after t years is given by the function , where m is the initial mass and h is the half-life in years. Cobalt-60 has a half-life of about 5.3 years. Which equation gives the mass of a 50 mg Cobalt-60 sample remaining after 10 years, and approximately how many milligrams remain?

; 13.5 mg
; 34.6 mg
; 0.2 mg
; 4.6 mg

Answer 1

General formula: M(t) = 50*(1/2)^(t/5.3).
After 10 years: M(10) = 50*(1/2)^(10/5.3) ≈ 50*(0.2707) ≈ 13.5 mg.

Answer: 13.5 mg.