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Solving equations graphically: word problems


A piecewise function f can model the height (in meters) of an airplane during a flight. Here is the graph of f, where t is the number of minutes that have passed since takeoff.
A graph labeled f on an x y coordinate plane. The x-axis scales by twenty and y-axis scales by one thousand. The graph increases from point (zero, five hundred) to (ten, eleven thousand). It remains constant to the point (fifty, eleven thousand). It decreases to (sixty, ten thousand). It remains constant to (one hundred, ten thousand). It then decreases to (one hundred twenty, zero).
The airplane reaches a height of 5000 meters after approximately 4.5 minutes.
What is the other time the airplane reaches a height of 5000 meters?
Round your answer to the nearest ten minutes.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
minutes after takeoff