The half-life of a radioactive kind of antimony is 4 days. How much will be left after 12 days, if you start with 7,600 grams of it?
The half-life of a radioactive substance is the time it takes for half of the substance to decay.
In this case, the half-life of antimony is 4 days. Therefore, after 4 days, half of the antimony will decay, leaving you with 3800 grams (half of 7,600 grams).
After another 4 days (a total of 8 days), half of the remaining antimony will decay, leaving you with 1900 grams (half of 3800 grams).
After the next 4 days (a total of 12 days), half of the remaining antimony will decay, leaving you with 950 grams (half of 1900 grams).
So, after 12 days, if you start with 7,600 grams of antimony, you will be left with 950 grams.