Can anyone tell me the formula and what the symbols mean for the following problems?

Question

1. You have a 1/2 inch internal diameter hose at your home and water moves through it at 2.5 feet/sec when the faucet is fully turned on. If you leave the water running while you wash your car (15 min) how much water have you just used?

2. You are given a hydraulic jack which you'd like to keep in your car in case you have a flat. Your vehicle weighs 4500lbs, and you know the jack will have to lift 1500 lbs when you put it under the axle. The hand end cylinder of the jack is 1/2inch in diameter and the "work" end of the cylinder is 3.5 inches in diameter. It has an 8 inch long handle; the distance from the attachment point of the handle to the small piston of the jack is 1.5 inches. How much force will you have to apply to the end of the handle to lift the car and change a tire?

Q (volume flow rate) = V * A, where

A = pi * (D^2/4) is the cross sectional area of the hose

D is the hose diameter (0.5 inch = 1/24 foot)

V is the average flow velocity in the hose. (It is higher in the middle than at the wall)

If you have A in square feet and V in ft/s, your answer will be in cubic feet per second. Convert that to gallons/minute and multiply by the washing time (15 minutes) to get the answer in gallons.

i did
A=pi(1/48)^2=.0014
2.5 ft/sec * .0014ft
.0035 ft^3

450 galmin/1 ft^3/sec * .0035 ft^3/sec*15 min
= 23.625 gpm