Algebra 2 word problem

Question

Half-Life

N(t)=No(12)thN(t)=No(12)th

N=N= final amount

No=No= initial amount

t=t= time

h=h= half-life

Iodine-123 is sometimes used in thyroid scans and has a half-life of 14 hours.

a) How much of a 180 mg sample would remain after 35 hours (round to hundreths)?

b) How much time does it take for 180 mg to decay to 93 mg (round to the nearest hour)?  Use logarithms to solve it algebraically. You must show your work for each step to get credit. 

Answer 1

N = 180(0.5)^35/14

93 = 180(0.5)^t/14