00:01
In this question, we want to use rubidium and strontium to date a rock from the moon.
00:10
Right, we are given that the amount or number of atoms for the rubidium per gram is about 1 .82 times 10 power of 10.
00:23
On the other hand, for strontium, it's 1 .07, 10 power of 9.
00:29
So we are basically going to look at the date or the time taken for rubium to decay by this amount.
00:41
Basically because rubium decays directly to strontium via the beta decay.
00:49
So the amount of strontium we're going to assume is all from the decay of rubidium.
01:03
This is one of the main assumptions.
01:05
There is no shrontium at the start and that all of them comes from rubidium.
01:16
So therefore we can find the original concentration of rubidium.
01:23
Chupay equals to just 1 .2 plus 1 .07.
01:51
And magna use this to find the time since we know the current number of rubidium...