Posted by BecKi on .
medication duration using the function of e through time lapse
problem D(h)=8e(up carrot)0.31(h)
find med level at 1 hour no problem 5.88mg. but every time I insert 4 for the 4 hours I get a larger number... much larger indicting the med level has gone up.
I am sure it is my bad math not the patient begining kidney failure. any help would be apprecitated.
bjm

PreCalc 
Reiny,
When h = 4 I get D(4 = 2.315
must be the way you are entering the values for calculations on your calculator.
On mine, an old "Sharp", I did:
2ndF
ln
(±.31x4)
=
x
8
= 
PreCalc 
MathMate,
It helps to find the problem if you posted what you've got, even if the number is much larger.
If you are using a calculator, I suspect the "minus" sign before the 0.31 had been left out.
The given formula is:
D(h) = 8e^{0.31h}
For h=1, 5.87 is correct.
For h=4,
8e^{0.31*4}
=8e^{1.24}
=2.32
If the minus sign is left out, it would have given 27.64 instead.