the number of combinations of n items chosen r at a time is the quotient of n factorial and the product of r factorial and the factorial of the difference of n and r

Which part of a 2-column proof is the hypothesis of the conjecture? a) given b) reasons c) prove d) statements ! i think it's b but i'm not quite

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

You buy 4 items that cost 2.69 14.45 8.05 13.95 what is the estimated total round to the nearest dollar