To round 3.892 to the nearest tenth, look at the digit in the hundredths place (which is the second digit to the right of the decimal point). In this case, the digit is 9.
Since 9 is greater than or equal to 5, we round the tenths place (the first digit to the right of the decimal point, which is 8) up by 1.
So, 3.892 rounded to the nearest tenth is:
3.9