The base of a pyramid-shaped tank is a square with sides of length 9 feet, and the vertex of the pyramid is 12 feet below the base. the tank is filled to a depth of 4 feet, and water is flowing into the tank at the rate of 3 cubic feet per second. find the rate of change of the depth of water in the tank.

Under normal conditions, 1.5 feet of snow will melt into 2 inches of water. during a winter season high in the mountains, 301 feet of snow fell. how many inches of water will there be when the snow melts?

Jude is making cement for a driveway. the instructions show the amount of each ingredient to make 1 batch of cement. complete each statement to adjust the ingredients for each new situation if jude uses these instructions.

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?