Question

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

Answer 1

The percent uncertainty of a blood pressure measurement of 120 mm Hg with an uncertainty of ±2 mm Hg is 1.67%. Using this percentage, the uncertainty in a blood pressure measurement of 71 mm Hg would be ±1.2 mm Hg, after rounding to one decimal place.

Step-by-step explanation:

To calculate the uncertainty in a blood pressure measurement of 71 mm Hg, given the percent uncertainty is the same as that for a measurement of 120 mm Hg with an uncertainty of ± 2 mm Hg, we first find the percent uncertainty of the original measurement.

The percent uncertainty is calculated by dividing the uncertainty by the actual measurement and then multiplying by 100 to get a percentage:

Percent Uncertainty = (Uncertainty / Measurement) × 100

For the measurement of 120 mm Hg, the percent uncertainty is:

(2 mm Hg / 120 mm Hg) × 100 = 1.67%

Assuming the same percent uncertainty for a blood pressure measurement of 71 mm Hg, you would use the same percentage to find the uncertainty:

Uncertainty = Percent Uncertainty × Measurement / 100

Uncertainty in 71 mm Hg = 1.67% × 71 mm Hg / 100 = 1.187 mm Hg

Since we typically round to the nearest whole unit or significant digit the uncertainty would be ± 1.2 mm Hg (rounded to one decimal place).

Answer 2

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

Step-by-step 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