Given
The half life is T=5715 years
The initial amount is N=50 g
To find
1) How much of it remains after 1600 years?
(2) How much of it remains after 16000 years?
Step-by-step explanation
The amount of carbon remains after t yaers is

1. Thus putting t=1600 years

2.Putting t=16000

Conclusion
1.Amount remains after 1600 year is 41.208 g
2.Amount remains after 16000 year is 7.184 g