## Calculus with Applications (10th Edition)

$\mu=20$ $\sigma=20$ $P(\mu \leq t \leq \mu + \sigma) \approx 0.233$
We are given $f(x)=0.05e^{-0.05t}; [0;\infty]$ The mean of the distribution: $\mu=\frac{1}{0.05}=20$ The standard deviation of X is $\sigma=\frac{1}{0.05}=20$ The probability of the random variable between 1 standard deviation above the mean: $P(\mu \leq t \leq \mu + \sigma) = P(20 \leq t \leq 40) \approx 0.233$