Solution for Problem 4.2.3

The concentration x of a certain drug in an organ after t minutes is given by
x = 0.05(1 - e-0.2t ). Find the concentration of the drug at 30 minutes.

Solve

Step
Find x using x = 0.05(1 - e-0.2t )      Given concentration formula
 Identify each part
  
t = 30
 Given
x = 0.05(1 - e-0.2(30) ) » 0.0226 Concentration formula


Interpret Þ There would be about 2% of the drug remaining in the organ after 1 hour.

    Calculator Help

Most calculators....use ^ or xy for exponent key
HINT: use these key strokes
0.05×(1 - e ^ (-0.2×30))   [enter or =]
You need both sets of parentheses.