How old is a rock with a half life of 5,280 years
if 1/8th of the parent material is left?

A rock with a half-life of 5,280 years having 1/8th of the parent material left will be 15,840 years old.

Explanation:

The half-life of a material is the time needed for only half of the parent material to be left, while half has is gone, or rather has disintegrated. The half-life is used further into the falling apart of the parent material though, with the same principle being applied. Practically, from the 1/2 of the parent material being left, the half-life of it would mean 1/4 of the parent material being left, and from that 1/4, the half-life would be at 1/8 of the parent material being left, and so one, by simply dividing in two.

In this case, having a half-life of the rock of 5,280 years, we will simply need to add that amount of years on every next phase. So, the half-life is 5,280 when 1/ of the parent material is left. When 1/4 of the parent material will be left we will have an age of 10,560 years, while when only 1/8 is left, we will have 15,840 years of age for the rock.

just took the test the answer is b.

since there isn't any suggested answers i will give you the reason and hopefully you can figure it

south africa, or rather all of africa, has not been in the location in which it is nowadays throughout the geological past. after the super-continent pangaea started to break apart, gondwanaland, in which was africa, moved further south, and parts of it came to be very close to the south pole. because the climate in this part of the world is very cold due to the very dispersed sun rays in there, what is now south africa, started to freeze, and the conditions were right for the formation of glaciers. the glaciers existed up until the period when gondwanaland started to break apart and what is now africa started to move towards north, sp it warmed up and the glaciers melted.