An old campfire is uncovered during an archaeological dig. Its charcoal is found to contain less than 1/1000 the normal amount of
. Estimate the minimum age of the charcoal, noting that 
Answer:
57300 years
Step-by-step explanation:
Using the relation of an half-life time in relation to fraction which can be expressed as:

here;
N represents the present atom
represents the initial atom
t represents the time
represents the half - life
Given that:
Its charcoal is found to contain less than 1/1000 the normal amount of
.
Then ;

However; we are to estimate the minimum age of the charcoal, noting that 
so noting that
, then:



If

Then

Therefore, the estimate of the minimum time needed is 10 half-life time.
For
, the normal half-life time = 5730 years
As such , the estimate of the minimum age of the charcoal = 5730 years × 10
= 57300 years