Final answer:
The measured number 61.15 L is rounded to three significant figures as 61.2 L, where the rounding of the last digit is influenced by the digit that follows it (in this case, 5).
Step-by-step explanation:
To round the measured number 61.15 L to three significant figures, we must look to the fourth figure (which is a 5) to decide how to round the third figure. The third figure is a 1 (from the decimal .15), and since the fourth figure is 5, we increase the third figure by 1. Therefore, 61.15 L rounded to three significant figures is 61.2 L. When rounding off a number to a certain number of significant figures, it is essential to identify the least precise measurement and adjust the final answer accordingly. In the examples provided, rounding rules are applied to ensure that the result is as precise as the least precise number used in the calculation.