Answer: 15.065 grams
Explanation:
Given: Jose and Alexia needed to weigh three samples of rock to the nearest thousandth.The weight of the first sample = 3.346 grams
The weight of the second sample = 2.479 grams
The weight of the third sample = 9.240 grams
Add all together such that the total weight=

⇒The total weight of the samples = 15.065 grams.
Therefore, the samples weigh 15.065 grams altogether.