One beaker contains 19.93 ml, another contains 14.0 ml and a third contains 10.6 ml. what is the total volume of the three beakers? select the answer with the correct number of significant digits.

Explanation:

When adding or subtracting values, you must round your answer to the same "place" as the measurement with its last significant figure furthest to the left.  

That is, you round off to the same number of decimal places as the measurement with the fewest decimal places.

The measurements of 14.0 and 10.6 have one digit after the decimal point, so you round the sum to have only one digit to the right of the decimal.

The number to be dropped (3) is less than 5, so you drop it.