Answer:
The length of the full-size train is 140 meters.
Explanation:
To determine the length of the full-size train, we will use the given relationship between the train at the amusement park and the full-size train.
From the question,
0.15 meter on the train at the amusement park represents 1 meter on the full-size train,
Let the length of the full-size train be x
Now,
If 0.15 meter on the train at the amusement park represents 1 meter on the full-size train
Then, 21 meters on the train at the amusement park will represent x meters on the full-size train
0.15 × x = 21 × 1
0.15x = 21
x = 21/0.15
x = 140 meters
Hence, the length of the full-size train is 140 meters.