Question

(a) A person’s blood pressure is measured to be 120±2mm Hg. What is its percent uncertainty? (b) Assuming the same percent uncertainty, what is the uncertainty in a blood pressure measurement of 80mm Hg?

a) (a) 1.67%; (b) 1.33mm Hg
b) (a) 1.67%; (b) 2.67mm Hg
c) (a) 2.0%; (b) 2.67mm Hg
d) (a) 2.0%; (b) 1.33mm Hg

Answer 1

The percent uncertainty of a blood pressure measurement of 120 ± 2 mm Hg is approximately 1.67%. Using the same percent uncertainty for a measurement of 80 mm Hg results in an uncertainty of about 1.33 mm Hg.

Step-by-step explanation:

To calculate the percent uncertainty of a blood pressure measurement, we can use the formula: percent uncertainty = (absolute uncertainty / measured value) × 100%. For a blood pressure measured as 120 ± 2 mm Hg, the calculation would be (2 / 120) × 100%, which equals approximately 1.67%.

For part (b), assuming the same percent uncertainty, we apply the same percentage to the different measured value of 80 mm Hg. This means the uncertainty in a blood pressure measurement of 80 mm Hg would be (1.67% of 80 mm Hg). Calculating this, we get 0.0167 × 80 mm Hg, which is approximately 1.33 mm Hg.

Therefore, the correct option is (a) 1.67%; (b) 1.33 mm Hg.