It's time for santa to deliver his presents. assuming he delivers presents all over the world, he has to travel about 75,000,000 miles. if he travels east to west, he can use the time zones to make christmas day last 31 hours. what speed, in miles per hour, must santa fly to get all of his presents delivered?

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.)