Susan buys black olives for $ 3 a pound and green olives for $ 5. a pound. $ 25 is spent. Buy 7 pounds total.
How many pounds of each type of olive did he buy?

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”?