A race car reaches the finish line and the driver slows down to come to a stop. If it takes the car 10 seconds to stop at a constant acceleration of -12mph/s. What was the car's speed at the finish line?

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)