Final answer:
The temperature 30 minutes after the cold front would be 55°F. This is found by subtracting the total temperature decrease over 30 minutes (20°) from the original temperature of 75°F. Therefore, the temperature 30 minutes after the cold front moved through was 55°F.
Step-by-step explanation:
The student needs to calculate the temperature 30 minutes after a cold front has passed through. Since the temperature dropped from 75°F at a consistent rate of falling 2/3 of a degree each minute, the total drop in temperature can be calculated using the expression (− 2/3) × 30. To find the temperature after 30 minutes, we begin with the original temperature and subtract the amount of change.
Original temperature = 75°F
Temperature drop = (2/3 degree/min) × 30 min = 20 degrees
New temperature = 75°F – 20° = 55°F
Therefore, the temperature 30 minutes after the cold front moved through was 55°F.