Answer: D. 6.5 g
Step-by-step explanation:
From the given table , weight of sample 1 = 1.25050 g
Weight of sample 2 = 2.50055 g
Weight of sample 1 = 2.74099 g
The total weight of all the 3 samples= 
Therefore, the total weight of all the 3 samples= 
Since, 
Thus, the estimated total weight of all 3 samples= 6.5 g