Sally went souvenir crazy on her trip to Mexico. She not only wasted good money on a sombrero
that had blinking lights on it, she also agreed to
pay a special 20% export tax. If Sally paid
$9.60 in tax, how much must the sombrero
have cost?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?