A store is having a sale in which all items are discounted 20%. Including tax, Colin paid $21 for a picture. If the sales tax rate is 5%, what was the original price of the picture?

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”?