Final answer:
The number 38,160,000 is written as Thirty-eight million one hundred sixty thousand and rounded to one decimal place is Thirty-eight point one million.
Step-by-step explanation:
The number 38,160,000 can be written using the number word million as Thirty-eight million one hundred sixty thousand. However, when we are rounding to one decimal place, we consider only the million and the hundred-thousand place since the hundred-thousand place will determine how the million place is rounded. The hundred-thousand digit is a 1, which is less than 5, so it doesn't cause the million figure to round up.
Therefore, when rounded to one decimal place, the number becomes Thirty-eight point one million (38.1 million).