Answer:
A skeleton that has lost 50% of its carbon-14 is 5750 years old.
Step-by-step explanation:
The halflife on an element is the amount it takes to decrease to half it's original amount, that is, when the amount is 50% of the initial amount.
How old is a skeleton that has lost 50% of its carbon-14?
If the skeleton lost 50% of its carbon-14 it has the other 50%, that is, it is in it's half-life.
The radioactive element carbon-14 has a half-life of 5750 years.
This means that a skeleton that has lost 50% of its carbon-14 is 5750 years old.