A ​30% dye solution is to be mixed with 60 ​% dye solution to get 120 L of a 50% solution. How many liters of the ​30% and 60​% solutions will be​ needed?

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”?