Answer :
a quantity of carbon - 14 will take 1342.5 years to become 1/8 of its original size.
Step-by-step explanation:
1/2 of the atoms decayed after 5370 years
now half of( 1/2 of )the atoms decayed after 5370/ 2 years
i.e, 1/4 of the atoms decayed after 2685 years.
again half of (1/4 of the atoms ) decayed after 2685/2 years
i.e, 1/8 of the atoms decayed after 1342.5 years.