Final answer:
The altimeter reading during the flight would be 400 feet higher than the reading at the point of departure.
Step-by-step explanation:
The altimeter measures the pressure of the atmosphere to determine the altitude of an aircraft. The altimeter reading is affected by the current altimeter setting, which represents the atmospheric pressure at the point of departure. In this question, the altimeter setting at the point of departure is given as 29.90 inches of mercury, while the current altimeter setting is stated to be 30.30 inches of mercury.
To calculate the altimeter reading during the flight, we need to compare the altitude difference caused by the change in altimeter setting. For each change of 1 inch of mercury in the altimeter setting, the altimeter reading changes by approximately 1,000 feet. Therefore, the difference in altimeter setting in this question is 0.40 inches of mercury, which corresponds to an altitude change of 400 feet.
The altimeter reading during the flight would be higher than the reading at the point of departure by 400 feet, as the current altimeter setting is higher than the departure altimeter setting. Therefore, if the altimeter was initially reading 0 feet at the point of departure, it would now read 400 feet during the flight.