There is a bag with only red marbles and blue marbles. The probability of randomly choosing a blue marble is 1 12 . There are 84 marbles in total in the bag and each is equally likely to be chosen. Work out how many red marbles there must be.

Gravel is being dumped from a conveyor belt at a rate of 25 ft3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. how fast is the height of the pile increasing when the pile is 14 ft high? (round your answer to two decimal places.) ft/min