Calculus
posted by Anonymous .
The radioactive element polonium decays according to the law given below where Q0 is the initial amount and the time t is measured in days.
Q(t) = Q0 ยท 2(t/140)
If the amount of polonium left after 700 days is 45 mg, what was the initial amount present?
mg

Q0 2^(700/140) = 45
Note that 700 days is 5 halflives
So, 1/32 of Q0 is left
Q0 = 32*45 = 1440