Final answer:
The average speed of Lisa's trip to the cabin is calculated to be 54 km/h, which is obtained by dividing the distance of 270 km by the time taken of 5 hours. This speed is not listed in the provided options.
Step-by-step explanation:
The question asks us to find the average speed of Lisa's trip to her cabin by a lake when we know her return trip conditions. To solve this, we will use the formula:
Average Speed = Total Distance / Total Time
Since the distance to the cabin and back is the same, we can denote the distance one way as d. We know that the return trip took 6 hours, and she traveled at 45 km/h, so the return distance (d) is 45 km/h × 6 h = 270 km. Now that we have the distance, we can find the speed for the trip there. It took Lisa 5 hours to travel the same distance:
Average Speed for trip there = d / Time for trip there
Average Speed for trip there = 270 km / 5 h = 54 km/h
The correct answer to the student's question is not listed among the options, as the average speed of the trip there is 54 km/h, which is faster than any of the options provided.