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Which of the following are parts of a sphere

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”?

The median am of triangle ∆abc is half the length of the side towards which it is drawn, bc . prove that triangle ∆abc is a right triangle, and find angle mac and abm