# Math Help - Confidence interval

1. ## Confidence interval

The number of hours for which an electronic device can retain information has a uniform distribution over the range [m -10, m +10], but the value of m is not known.
(a) Show that the variance of the number of hours for which the device can retain the information is 100/3.

2. Originally Posted by Sashikala
$E(X) = \mu$ and $E(X^2) = \mu^2 + \frac{100}{3}$.