Final answer:
Without the specific trial times, it's not possible to calculate the average time it took for the car to travel the given distances. If we had the data and the answer 1.39 seconds was the average of said data, then option b) would be correct, but this cannot be confirmed with the information provided.
Step-by-step explanation:
The question doesn't provide the necessary data to calculate the average time for the car to travel 0.25 meters or 0.50 meters with four washers attached to the pulley. To determine the average time taken, you would need the individual times that it took for the car to travel these distances with the given setup, and then calculate the mean of those times.
However, assuming that we had the correct measurements, the calculation process would involve adding the times recorded for each trial and then dividing by the number of trials to find the average. If the option of 1.39 seconds was provided for the average time it took the car to travel 0.50 meters, and assuming the available data and context support this, then the correct choice would be: b) 1.39 seconds. It's important to mention, without the specific data, we cannot confirm this answer to be correct.
For example, if the car was timed twice for the 0.50 meter distance and the times were 1.35 seconds and 1.43 seconds, the average time would be calculated as (1.35 + 1.43) / 2 = 1.39 seconds, which matches option b).