A radioactive substance decays at a rate of 30% per year. Presently there are 400 grams of the substance. How do you find the amount left after 8 years?

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Answer 1 · 2016-07-30T08:37:57

At the end of #8# year amount left
#=400(1-0.3)^8#
#=400(0.7)^8#
#=400(0.0576)# grams
#=23.04# grams