A study of cars arriving at a parking structure at the local airport shows that the time between arrivals is 1.2 minutes and is exponentially distributed. The probability that more than 2 minutes will elapse between the arrivals of cars is about 0.81.

Question

Quizplus · Accepted Answer

The exponential distribution is given by the formula $P(X > x) = e^{-\lambda x}$, where $\lambda = 1/\text{mean}$ and the mean time between arrivals is 1.2 minutes. Thus, $\lambda = 1/1.2$. For $x = 2$ minutes, $P(X > 2) = e^{-(1/1.2) \cdot 2}$ which calculates to approximately 0.3012, not 0.81.

A Study of Cars Arriving at a Parking Structure at the Local