Answer: 2.7 days
Explanation:
You'd divide 100 g by 2 until you reach 6.25 g:
100/2
=
50
;
50/2 (fraction
=
25
;
25/2(fraction
=
12.5
;
12.5/2 (fraction
=
6.25
Since there were four 2s, divide 10.8 days by 4:
10.8 days
4
=
2.7 days
100 g of Au-198 would have a half life of 2.7 days.