Lifetimes x (hours) of a certain alkaline battery are values of a random variable X that is approximately exponentially distributed with = 20 hours. The expected value of X = = The standard diviation of X = Determine the probability that an alkaline battery will last more than 15 hours. Determine the probability that an alkaline battery will last between 10 and 15 hours. Solution The expected value of X =1/20=0.05.

1. Lifetimes x (hours) of a certain alkaline battery are values of a random variable X that is
approximately exponentially distributed with = 20 hours.
The expected value of X = =
The standard diviation of X =
Determine the probability that an alkaline battery will last more than 15 hours.
Determine the probability that an alkaline battery will last between 10 and 15 hours.
Solution
The expected value of X =1/20=0.05