Solve 7x²+8x+1=0 using quadratic formula

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

Abag contains 10 white golf balls and 6 striped golf balls. a golfer wants to add 112 golf balls to the bag. he wants the ratio of white to striped gold balls to remain the same. how many of each should he add?

How is the interquartile range calculated?