If the Mean of an Exponential Distribution Is 4, Then $\lambda$

Short Answer

If the mean of an exponential distribution is 4, then the value of the parameter $\lambda$ is: $\begin{array}{|l|l|}\hline\text { A. } & 4 . \\\hline \text { B. } & 0.25 . \\\hline \text { C. } & 2 . \\\hline \text { D. } & 0.5 . \\\hline\end{array}$