math
posted by becky .
the half life of the carbon isotope C14 is about 5700 years.
A. about how many years does it take 1000 grams of this substance to decay to 500 grams?
B. about what percent of the original amount would you expect to find after 1000 years?

A. ummmhhh, 5700 years
(you said the halflife was 5700 years , 1000 g went to half, namely 500g)
b)
amount = 1000 (1/2)^(t/5700)
= 1000(1/2)^(1000/5700)
= 885.5 g
so 88.55% would remain after 1000 yrs