# Math Help - Confidence interval

1. ## Confidence interval

Could you please help me on the following problem?
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
Could you please help me on the following problem?
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.
$E(X) = \mu$ and $E(X^2) = \mu^2 + \frac{100}{3}$.

Get these by integrating the pdf.

3. ## Confidence interval

Thanks very much.
I got the variance as follows:square(b-a)/12
square[10-(-10)]/12 = 100/3