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2022 AMC 10B Question 23

AMC10 · 2022 AMC 10B

Question 23

Ant Amelia starts on the number line at $0$ and crawls in the following manner. For $n=1,$ $2,$ $3;$ Amelia chooses a time duration $t_n$ and an increment $x_n$ independently and uniformly at random from the interval $(0,1).$ During the $n$th step of the process, Amelia moves $x_n$ units in the positive direction, using up $t_n$ minutes. If the total elapsed time has exceeded $1$ minute during the $n$th step, she stops at the end of that step; otherwise, she continues with the next step, taking at most $3$ steps in all. What is the probability that Amelia’s position when she stops will be greater than $1?$
  1. $ \dfrac 13 $
  2. $ \dfrac 12 $
  3. $ \dfrac 23 $
  4. $ \dfrac 34 $
  5. $ \dfrac 56 $