As
increases, [y] is expected to increase.
17 are older than 16 years old and 12 are taller than 170 cm
Just subtract 622 feet from 486 feet to get the change in elevation. The result will be negative because your friend's house is at a lower elevation than yours.
Now find the mean change in elevation per mile by dividing (486 ft - 622 ft) by 4 miles:
-136 ft
----------- = -34 ft/mile
4 mi
