00:01
So cobalt 60, question 42, cobalt 60, half -life is 10 .47 minutes.
00:08
That is a four right here.
00:11
How many milligrams of cobalt 60 will remain after a certain amount of time, which is 104 .7 minutes in a 10 -gram sample.
00:22
So very straightforward.
00:26
So you're given the half -wife, you're given a length of time.
00:29
So it takes, they're giving you 104 .7 minutes.
00:36
So when you're given the half -life and you're given the time, you can just do some division to figure out how many half -lives you have.
00:47
So you can say you have, all right, all right, i'll do this in green.
00:50
You have 104 .7 minutes.
00:56
And there is one half -life, sorry, i can't spell, not plural, one half -life per 10 .47 minutes.
01:15
So how many half -lives? how many half -lives is that? are that? how many half -lives is that? yeah, that works.
01:25
Ten -half -lives.
01:30
Lives.
01:32
Or five full lives.
01:33
No, it's not true.
01:36
My jokes are bad.
01:37
Just ignore me.
01:39
So when you go through 10 -half -lives, your sample is decreasing by 2, 10 times, if that makes sense...