Anumber , x, rounded to 1 decimal place is 3.7 what is the error interval for x

The error interval for x is:

                  [3.65,3.74]

The number after rounding off is obtained as:

                          3.7

We know that any of the number below on rounding off the number to the first decimal place will result in 3.7:

   3.65     3.66    3.67    3.68    3.69    3.70    3.71   3.72    3.73    3.74

( Because if we have to round off a number present in decimals to n place then if  there is a  number greater than or equal to 5 at n+1 place then it will result to the one higher digit  at nth place on rounding off and won't change the digit if it less than 5 )

         Hence, the error interval is:

             [3.65,3.74]

both equations and proportions are better.