Final answer:
Robert's average rate of elevation change while descending the 1380-foot hill in 30 minutes is calculated by dividing the total elevation change by the time. The result is 46 feet per minute, which is option A.
Step-by-step explanation:
To find Robert's average rate of elevation change, we need to divide the total change in elevation by the time it took to descend. Robert descends a 1380-foot hill in 30 minutes. To calculate the rate of elevation change per minute, we use the formula: Rate of elevation change = Total elevation change / Time, Substituting the given values: Rate of elevation change = 1380 feet / 30 minutes = 46 feet per minute. Therefore, Robert's average rate of elevation change is 46 feet per minute, which corresponds to option A.