Suppose the Length of Time That It Takes a Person $$f ( x ) = \left\{ \begin{array} { l l } \frac { 1 } { 4 } x e ^ { - x / 2 } & \text { if } x \geq 0 \\0 & \text { if } x < 0\end{array} \right.$$

Short Answer

Suppose the length of time that it takes a person to complete a hedgerow maze is measured by a random variable X that is exponentially distributed with a probability density function $$f ( x ) = \left\{ \begin{array} { l l } \frac { 1 } { 4 } x e ^ { - x / 2 } & \text { if } x \geq 0 \\0 & \text { if } x < 0\end{array} \right.$$ where x is the number of minutes a randomly selected person takes to complete the maze. Find the probability that a randomly chosen person will take less than 4 minutes to complete the maze.