medication eliminated exponentially, w/ half-life of 36 hrs

[going crazy]

The drug Valium is eliminated from the bloodstream exponentially withy a half-life of 36 hours. Suppose that a patient receives an initial dose of 100 miligrams of Valium at midnight. A. how much valium is in the patient's blood at noon the next day? b. Estimate when the valium concentration will reach 60% of its initial level.

[nona.m.nona]

The drug Valium is eliminated from the bloodstream exponentially withy a half-life of 36 hours. Suppose that a patient receives an initial dose of 100 miligrams of Valium at midnight. A. how much valium is in the patient's blood at noon the next day? b. Estimate when the valium concentration will reach 60% of its initial level.

What is the exponential growth/decay equation? (Check here for a review.)

After thirty-six hours, how much of the original amount is left?

Plug in the time value, the initial value, and the half-life value. Solve the equation for the decay constant.

a) Plug the time (twelve hours), the initial amount, and the decay constant into the equation. Simplify to find the amount remaining.

b) Plug the desired final level, the initial level, and the decay constant into the equation. Then solve the exponential equation for the time value.

If you get stuck, please reply showing your work so far. Thank you.