The relative humidity would be % if the actual water vapor in the air was 4 grams per cubic meter, the air's capacity to hold water vapor was 8 grams per cubic meter and the dewpoint temperature was ~ 53 degrees fahrenheit.

50%

Explanation:

Humidity is the amount water vapor present in the atmosphere.

Relative humidity is defined as the ratio of partial water vapor present in air to the actual water vapor at a particular temperature. It is expressed in percentage and the higher the percentage RH, the more the saturated water vapor present in the atmosphere and vice versa.

It is expressed mathematically as shown;

RH = actual water vapor in air/saturated water vapor × 100%

If the actual water vapor in the air was 4 grams per cubic meter and the air's capacity to hold water vapor was 8 grams per cubic meter

Actual water vapor = 4g/cm³

Air's water capacity (saturated water vapor) = 8g/cm³

RH = 4/8×100

RH = 50%