To convert from inches of mercury to millimeters of mercury absolute, what must you do with the inches of mercury?

To convert from inches of mercury (inHg) to millimeters of mercury (mmHg), it is essential to recognize the relationship between these two units. One inch of mercury is equivalent to approximately 25.4 millimeters of mercury. Therefore, to convert inches of mercury to millimeters of mercury, you would multiply the value in inches by 25.4. However, the choice suggests an additional step to subtract the result from 760.

This subtraction aligns with the concept of absolute pressure measurement. Standard atmospheric pressure is defined as 760 mmHg, so when converting to absolute pressure, one needs to consider how many millimeters are represented in the context of standard atmospheric pressure. The conversion helps to ensure that you express the measurement accurately in terms of what is above or below atmospheric pressure.

Thus, to complete this conversion correctly, the process described in the choice captures the necessary steps to arrive at the correct absolute pressure reading by first calculating the equivalent millimeters of mercury then effectively utilizing standard atmospheric pressure for context.