Checkout times in a Walmart store follow an exponential distribution with a mean time of 8 minutes.What is the probability that the checkout time for the next customer will be 6 minutes or less?
A)0.528
B)0.472
C)0.972
D)0.328

Question

Quizplus · Accepted Answer

The exponential distribution probability function is given by $P(X \leq x) = 1 - e^{-\lambda x}$, where $\lambda = \frac{1}{\text{mean}}$. Here, the mean checkout time is 8 minutes, so $\lambda = \frac{1}{8}$. For a checkout time of 6 minutes or less, $P(X \leq 6) = 1 - e^{-\frac{1}{8} \cdot 6} = 1 - e^{-\frac{3}{4}} \approx 0.528$.

Checkout Times in a Walmart Store Follow an Exponential Distribution