The amount A, of 70 grams of a certain radioactive material remaining after t years can be found by the equation A=70(0.62)^t. When will 10 grams remain?

Answer 1

just find t where

70*0.62^t = 10
.62^t = 1/7
t log.62 = log 1/7
t = log(1/7)/log(.62) = 4.07