The error in rounding a number is half of the unit of measure. The number was rounded to the nearest 0.1 unit so the error is half of 0.1 which is 12⋅0.1=0.05 2 1 ⋅0.1=0.05. Since 3.7+0.05=3.75 3.7+0.05=3.75 and 3.7−0.05=3.65 3.7−0.05=3.65, then the error interval is \boxed{3.65\le x<3.75}.
