question is herehttpimgurcoma8ePpU Sodium24 is a radioactive

question is here..http://imgur.com/a/8ePpU

Sodium-24 is a radioactive substance used for medical purposes. Suppose that a patient is injected with sodium-24 at t = 0 and that the amount of sodium-24 in the patient\'s body in milligrams is given by S(t) = 5e-^0.35t where t is the time in hours. How long will it be until there are only 0.1 milligrams of sodium-24 remaining in the patient\'s body? 4.8 hours 11.2 hours 2.9 hours 3.9 hours

Solution

The decay equation : S(t) = 5e^-0.35t

where t is the time in hours.

S(t) = 0.1 milligms ; solve for t:

0.1 = 5e^-0.35t

0.02 = e^-0.35t

take natural log on both sides:

ln0.02 = -0.35t

t = 11.177 = 11.2 hours

Option B