Final answer:
The expression 42.17 + 31.9 evaluates to 74.07, ensuring the answer is given to the correct number of significant figures, which is to the nearest hundredths place.
Step-by-step explanation:
The student is asking for the evaluation of the mathematical expression: 42.17 + 31.9. To correctly evaluate this expression and report the answer with the proper number of significant figures, we can perform the following steps:
Align the decimal points of both numbers when adding them together.
Perform the addition operation: 42.17 + 31.9 = 74.07.
Ensure that the answer has the correct number of significant figures, which in this case should be to the nearest hundredths place, as both numbers in the expression have at least two decimal places.
Therefore, the correct answer to the expression 42.17 + 31.9 is 74.07.