To express the federal debt amount of Country C, which is $278,560,125,000, in the form of a single digit times an integer power of 10, we start by determining the proper form.
The number can be simplified as follows:
- Identify where the decimal point needs to be placed to have only one non-zero digit before it. In this case, we move the decimal point in 278,560,125,000 to after the '2', resulting in 2.78560125.
- Now we express the number as \(2.78560125 \times 10^{11}\), since moving the decimal point 11 places to the left gives us that value.
Next, we need an estimation, which typically rounds to a more manageable form. The number 2.78560125 can be rounded to 2.79 for this estimation.
Thus, the closest estimation of the federal debt amount in the required scientific notation format is:
2.79 × 10^11
So the correct response is:
2.79 × 10^11.