If you would like to know the mean change in elevation per minute, you can calculate this using the following steps:
1200-foot ... 3 minutes
x-foot = ? ... 1 minute
1200 * 1 = 3 * x
1200 = 3 * x
x = 1200 / 3
x = 400-foot
The correct result would be 400-foot per minute.
