The half-life of a radioactive kind of barium is 3 minutes. If you start with 9,152 grams of it,
how much will be left after 12 minutes?

After 12 minutes, you would have gone through four half-lives (since 12 divided by 3 equals 4). Each half-life reduces the amount by half. So, starting with 9,152 grams:

1st half-life (3 min): 9,152 g / 2 = 4,576 g
2nd half-life (6 min): 4,576 g / 2 = 2,288 g
3rd half-life (9 min): 2,288 g / 2 = 1,144 g
4th half-life (12 min): 1,144 g / 2 = 572 g

So, after 12 minutes, you would have 572 grams of barium left!

To make this calculation easier to remember, think of it as a game of “hot potato,” where each half-life takes away half the weight. It’s like passing the potato around until only a small piece is left. The more times you pass it, the smaller the piece gets! And hey, math is just a fun way to play with numbers!