To round a number to the nearest tenth, we look at the digit in the hundredths place and decide whether to round up or down. If the digit is 5 or more, we round up by adding 1 to the digit in the tenths place and dropping the rest of the decimals. If the digit is 4 or less, we round down by keeping the digit in the tenths place and dropping the rest of the decimals.
Some possible numbers that round to 3.9 when rounding to the nearest tenth are:
3.85
3.86
3.87
3.88
3.89
3.90
3.91
3.92
3.93
3.94
Sorry if i could not get a direct answer, theres just many answers to this question.