Posted by kayse on .
This question involves the halflife formula. In this exercise, we are to give a halflife for an exponentially decaying quantity. Need answer to the following: The halflife of a drug in the bloodstream is 4 hours. By what factor does the concentration of the drug decrease in 24 hours? in 36 hours?

linear/exponential 
bobpursley,
If you want to use the formula...
amount remaining= origamount*e^(.692t/4)
put in the t, and solve.
Another way is
amountremaining= (1/2)^t/4
when t=24
amountremaining= 1/2^(6)= 1/64 th