I love helping people how do the circumference of a circle relate to the area of square?

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”?

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.

28 x 12 + 34 = ? it's for a test that if i fail on i will not proceed into the honor roll society i always dreamed of!me! worth 50 !