Question 90691
half-life means that half of the original material will be gone in the stated time


the formula is a=A((1/2)^(t/h)) where a is the amount remaining, A is the starting amount, t is the time , h is the half-life


a)  a=100(.5^(3/4))=100(.595)=59.5


b)  a=100(.5^(7/4))=100(.297)=29.7


2)a)  h=120(1-e^((-.04)30))=120(1-e^(-1.2))=120(1-.301)=83.9


2)b)  h=120(1-e^((-.04)100))=120(1-e^(-4))=120(1-.0183)=117.8


2)c)  h=120(1-e^((-.04)150)=120(1-e^(-6))=120(1-.00248)=119.7