the dot plot displays the lengths of pencils (in inches) used by students in a class what is the mean?

This is geometry. could anyone ? i can't fail this class. my grade is quite low already.

Which representation has a constant of variation of -2.5

Aball is thrown from a height of 139 feet with an initial downward velocity of 15 ft/s. the ball's height h (in feet) after t seconds is given by the following. h=139-15t-16t^2 how long after the ball is thrown does it hit the ground? round your answer(s) to the nearest hundredth. (if there is more than one answer, use the "or" button.) t =