Observation: You saw/ observed something and you are stating that.
Inference: You are predicting something to be true. If so and so, then this will occur.
Answer:

Explanation:
Ok, the average speed can be calculate with the next equation:
(1)
Basically the car cover the same distance "d" two times, but at different speeds, so:

and the total time would be the time t1 required to go from A to B plus the time t2 required to go back from B to A:

From basic physics we know:

so:


Using the previous information in equation (1)

Factoring:
(2)
Finally, replacing the data in (2)

Taking ratio of W & w. ≈ 6 . w = 1/6 W. Therefore , Weight of an object on the moon is 1/6 of its weight on the earth.