Problem #21: Jaws
A seaside resort along the Pacific Ocean is equipped with an electronic
shark detection system which sounds an alarm on the average of 1 day out of
30. There are 10 times more false alarms than there are undetected sharks.
We also know that only three out of four sharks are detected. Given the above
information, what is the percentage of "peaceful" resort days if that term is
defined as days unmarred by alarms or sharks?