You use a millimeter ruler to measure the height of a rail curb. The bottom of the ruler is resting on the table. The place where the height measurement is taken is a little curved, so it is difficult to identify very precisely where the measurement should be taken. Also, it's a bit tricky to make sure the ruler is perfectly vertical (it might be leaning forward or backward a bit). When you take the measurement, you measure 12.9 mm. By moving the ruler a little, you are confident that the correct measurement is somewhere between 12.7 mm and 13.3 mm. Indicate the value that you will record in your logbook, as well as the uncertainty that you will attribute to it. Give your answers in mm. Warning: Keep at least 3 significant digits in your answers, even if it does not respect the rules of presentation of data in the laboratory.

You use a millimeter ruler to measure the height of a rail curb. The bottom of the ruler is resting on the table. The place where the height measurement is taken is a little curved, so it is difficult to identify very precisely where the measurement should be taken. Also, it's a bit tricky to make sure the ruler is perfectly vertical (it might be leaning forward or backward a bit). When you take the measurement, you measure 12.9 mm. By moving the ruler a little, you are confident that the correct measurement is somewhere between 12.7 mm and 13.3 mm. Indicate the value that you will record in your logbook, as well as the uncertainty that you will attribute to it. Give your answers in mm. Warning: Keep at least 3 significant digits in your answers, even if it does not respect the rules of presentation of data in the laboratory.