#### Answer

You would write the number describing the total volume as 2 significant figures (e.g. 3.2). The precision of the number is limited by the lowest number of significant figures in the numbers used in the original calculation.

#### Work Step by Step

To find the total volume using correct significant figures:
Graduated cylinder 1 shows $\approx 2.9$ mL
Graduated cylinder 2 shows $\approx 0.28$ mL
The lowest number of significant figures between both numbers is 2. Therefore the sum of the two numbers should be written as 2 significant figures when the volumes are added to the beaker.
$2.9$ mL + $0.28$ mL $\approx 3.2$ mL