At noon, a small plane leaves an airport and flies due east at 200 kilometers per hour. Two hours
later another plane leaves the same airport and
flies due south at 400 kilometers per hour. When
will the planes he 800 kilometers apart?

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”?