1. .Divide £24 into the ratio 1 : 3. (Total 4 parts) 2.Divide 800ml into the ratio 3 : 7. (Total 10 parts)
3.Share 56 sweets in the ratio 2 : 5. (Total 7 parts)
4.Divide £72 into the ratio 4 : 5. (Total 9 parts)

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”?