What is the answer for 4-8 and 6 is optional.. show work.. you(need answer asap)

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”?

Find each value of the five-number summary for this set of data. [note: type your answers as numbers. do not round.] 150, 120, 136, 180, 158, 175, 124, 162 minimum maximum median upper quartile lower quartile

Write the equation in general quadratic form: plz !