title: Failure rate of a system
body: <p>In a Microsoft interview I was asked the following question:</p>
  
  <p><em><strong>A system is guaranteed to fail 10% of a time within any given hour, what's the failure rate after two hours ? after a million hour ?</em></strong> </p>
  
  <p>I'm not very experienced in Reliability theory and Failure rates, but any input on this question will be very much appreciated. </p>