Question

The speed of a bullet train is measured to be 312.0 mpg +/- 3.9 mph. What is the percent uncertainty in this measurement?(1 point)
A 1.3 %
B .13 %
C 14.4%
D .14 %

Answer 1

To calculate the percent uncertainty in the measurement of the speed of the bullet train, we use the formula:

\[
\text{Percent Uncertainty} = \left( \frac{\text{Uncertainty}}{\text{Measured Value}} \right) \times 100
\]

In this case, the uncertainty is \(3.9 \, \text{mph}\) and the measured value is \(312.0 \, \text{mph}\).

Now, substituting the values into the formula:

\[
\text{Percent Uncertainty} = \left( \frac{3.9}{312.0} \right) \times 100
\]

Calculating that:

\[
\text{Percent Uncertainty} = \left( 0.0125 \right) \times 100 \approx 1.25\%
\]

Rounding to two decimal places, the percent uncertainty is approximately **1.3%**.

Therefore, the answer is **A 1.3%**.