Final answer:
The sum of 9.6, 2.9, and 12.8 is rounded to 25.3, and when this result is rounded to 1 significant figure, the answer is 30.
Step-by-step explanation:
The question asks to round the sum of 9.6, 2.9, and 12.8 to 1 significant figure.
First, we find the exact sum which is 9.6 + 2.9 + 12.8 = 25.3.
Now, to round this sum to 1 significant figure, we look at the first non-zero digit, which in this case is 2.
The number directly to its right is 5, which means we round the number up.
Therefore, the number 25.3 rounded to 1 significant figure is 30.
In general, when rounding to 1 significant figure, if the first non-zero digit is followed by a number 5 or greater, we round up. Otherwise, we round down.