Question

Doctors can use radioactive chemicals to treat some forms of cancer. The half life of a certain chemical is 5 days. A patient receives a treatment of 16 millicuries of the chemical. (A millicurie is a unit of radioactivity.) How much of the chemical remains in the patient 10 days later?

Answer 1

160 Chemical's remains in the patient...text back if this helps if not I will do some crazy research for you.

Answer 2

You'll need a half-life formula.  (See attached) (Use the formula at the bottom).

Ending Amount = Beginning Amount / 2 ^n
where "n" is the number of half-lives.
Half life is 5 days, so amount remaining after 10 days is
1/2^2 or 1/4 of the original is left