The ideal speed of an elevator is 120 feet/minute. But the elevator’s speed is allowed to vary by less than a certain amount. Identify the graph of the variance levels that indicate unacceptable elevator speeds.

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

Step-by-step 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

the answer is 13 cm