Archimedes was asked by his king to figure out a way of telling if people were giving him fake gold objects. That was when Archimedes discovered his famous principle: an object placed in water displaces the same volume of water as the object’s volume. Explain how Archimedes used this to solve his problem.

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”?