Help #3 - 5 please please

Karen will divide her garden into equal parts. she will plant corn in 8/12 of the garden. what is the lowest number of parts she can divide her garden into?

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”?

Layla answer 21 of the 25 questions on his history test correctly.what decimal represents the fraction of problem he answer incorrectly.