Answer:
Left to right ≤ -120 in f/s then ≤ 120 in f/s then ≥ -120 in f/s then ≥ 120 in f/s the unacceptable ones are represented in picture 1 and picture 3 as ≤ -120 in f/s and ≥ -120 in f/s this is because they are both decreasing to y = 0 at 120ft each
Explanation:
The ft/s are showing variance of speed inequalities shown in y coordinate as important as this show the change of 120ft in variance so that picture 2 and 4 both being increasing at 0-120 ft being above and below the line as both ways to show increase as inequalities of ≤ and ≥ to represent solid lines ( dotted lines represent other inequalities being < or >, ) so we show 2nd picture as lesser or equal to 120 as variance speed of elevator ≤ 120 in f/s as it is below the line and 4th picture to be as greater to 120 variance speed of elevator ≥ 120 in f/s The 1st picture is decreasing so and above the line so it is minus ≤ -120 and the 3rd picture is below the line and also decreasing so it is minus ≥ -120 in f/s so to find speeds that are unacceptable - we just show the negative values being picture 1 and picture 3