Assuming the same percent uncertainty and the same measurement device, what is the uncertainty in a blood pressure measurement of 71 mm Hg?

With a person's blood pressure is measured to be 120 ± 2 mmHg, it will be 1.2mmHg

Explanation:

What is missing in the question is the percentage of uncertainty.

If we assume that a person's blood pressure is measured to be 120 ± 2 mmHg, the percent uncertainty is computed as:

% uncertainty = 2mmHg/120mmHg x 100% = 1.7%

So,

The uncertainty in the blood pressure is = 1.7% / 100% * 71mmHg = 1.2mmHg