Can anyone help me with only 5 questions of exponential decay? Pleaseeee i'll give medals :(

Question

jhonyy9 · Answer

goooo

jhonyy9 · Answer

where are ???

anonymous · Answer

why is your picture a pic of your butt?

anonymous · Answer

yummmm

anonymous · Answer

A farmer in china discovers a mammal hide that contains 71% of its original amount of C-14.
Find the age of the mammal hide to the nearest year.

anonymous · Answer

do you know the half life or carbon 14?

bahrom7893 · Answer

e^(-kt) = 0.41

bahrom7893 · Answer

wait sorry
e^(-kt) = 0.71

bahrom7893 · Answer

kt = ln(1/0.71) = ln(1.408)

anonymous · Answer

i think it is 5700 years. if so solve 
$$.71=(\frac{1}{2})^{\frac{t}{5700}}$$ for t via 
$$\ln(.71)=\frac{t}{5700}\ln(.5)$$
$$t=5700\times \frac{\ln(.71)}{\ln(.5)}$$

anonymous · Answer

i get 2816 years

bahrom7893 · Answer

k= 0.0001
t = ln(1.408)/0.0001 = 3421

bahrom7893 · Answer

I got that, but I think satellite must be right

anonymous · Answer

no k is not .0001 that is rounding error

bahrom7893 · Answer

oh okay then satellite is right, i dunno the half life of C-14 just googled it and that was what i got

anonymous · Answer

it is easier in these problems to work with half lives.

anonymous · Answer

So it's 2816 years?

anonymous · Answer

that is what i got, yes.

anonymous · Answer

check my calculator work though