radioactive potassium -42 ,which is used by cardiologists as a tracer has a half-life of about 12.5 hours. If an office supply contains 100 gm at 9am tuesday how much will remain by 5 pm wednesday

Question

anonymous · Answer

using the half -life formua $$N= N0b^t/k$$

anonymous · Answer

yes. 
$$
N_0=\text{initial amount}=100\rm{gm}\
t=\text{amount of time}\
k = \text{half-life}=12.5\rm{hrs}
$$

anonymous · Answer

now, we need to find out how many hours it is from 9am Tuesday to 5pm Wednesday
$$t=24(1\rm{day})+(3\rm{hrs}+5\rm{hrs})=32\rm{hrs}$$
the important thing is to have the same units for "t" and "k"

anonymous · Answer

oh ok 
at first i had 12.5 for N0

anonymous · Answer

thats why i got confused

anonymous · Answer

k