Answer
After 3.8 days 1.23 g remain
After 7.6 days 0.613 g remain.
After 11.4 days 0.306 g of sample remains
Work Step by Step
Given sample mass = 2.45 g.
Half life of sample = 3.8 days.
So,
After 3.8 days 1.23 g remain
After 7.6 days 0.613 g remain.
After 11.4 days 0.306 g of sample remains