After shooting down the bird with a stone, Kerwin felt a great sense of achievement. “This is what a mathematician could do,” Kerwin picked up the dead bird and said, “l(fā)ook at you! What a beautiful creature! You would bring me a big fortune!” Then, Kerwin put the bird into his bag. Suddenly, he felt something unusual. “Why is there so quiet?” Kerwin said to himself. Kerwin stopped moving and nervously looked around. After a split second, Kerwin saw something that he would not forget for the entire lifetime. A tiger was staring at him on the back! “Oh, Jesus,” Kerwin immediately started running. “ I must call Lionel for help, otherwise I am going to die here! The tiger will catch me anyway,” Kerwin thought. In order to run faster, Kerwin threw away everything, including his bag that contained the beautiful bird. While running desperately, Kerwin took out his phone and called Lionel. “LIONEL! HELP ME!” “Calm down, Kerwin, I can’t hear what you said clearly.” “I CAN’T BE CALM! NOT RIGHT NOW! A TIGER IS CHASING ME!” “ Oh, Jesus, what can I do for you?” “ USE YOUR UNMANNED PLANE TO RESUE ME!? THE ONE THAT CAN FLY AT THE SPEED OF LIGHT!” “ All right, Kerwin, I will do it now. The unmanned plane will reach your position within 30 seconds. It will catch you on the ground. Jump when you see the plane diving towards you. I will set up the plane so that it would fly at the quadratic function h=0.2x2-1.6x+5.2, where h represents height and t represents time. Think out of a way yourself to make the plane catch you.” “COPY THAT!” Kerwin shouted. “ The tiger is still chasing me, so I can’t stop running,” Kerwin thought, “ so the only way for me is to jump while I am running. That way, my motion would also follow a quadratic function. In order to reach the plane, I cannot jump too high or too low. If I jump too high, the plane will hit me and kill me. If I jump too low, the plane won’t catch me. That is to say, the quadratic function that my motion follows must have only one intersection with the quadratic function that the plane follows. That would be h=-4x2+32x-62.”? After a split second, Kerwin saw the plane diving towards him. He jumped at the quadratic function that he previously figured out. The plane caught him perfectly. “HAHAHAHAHAHA! This is what a mathematician can do!” Kerwin yelled on the plane.