Final answer:
To get the answer with the correct number of significant figures for the calculation (84.1 s + 26.5 s) / (9.78 cm³ + 2.16 cm³), first sum each set of numbers, and then divide the results. The final result with the correct number of significant figures is 9.263 s/cm³.
Step-by-step explanation:
The calculation in question requires us to first understand how to add and divide numbers while paying attention to significant figures. When adding or subtracting, the result should have the same number of decimal places as the measurement with the fewest decimal places. For division and multiplication, the result should have the same number of significant figures as the measurement with the fewest significant figures.
First, we add the times: 84.1 s + 26.5 s = 110.6 s (4 significant figures). Then, we add the volumes: 9.78 cm³ + 2.16 cm³ = 11.94 cm³ (4 significant figures). Now we divide the sums to get our final answer: 110.6 s / 11.94 cm³ = 9.2629... s/cm³.
Since we are dividing, our result must have the same number of significant figures as the measurement with the fewest significant figures. Both sums have 4 significant figures, so our final result should also have 4 significant figures: 9.263 s/cm³.