The United States Coast Guard has discovered a growing circular oil slick near an oil tanker docked offshore at Los Angeles, California. The Coast Guard begins monitoring the the size of the oil slick and determines that the diameter of the oil slick is increasing at a constant rate. One hour after the oil slick was discovered by the Coast Guard it was 50 meters in diameter. Four hours after the oil slick was discovered the slick was 65 meters in diameter. What was the diameter of the oil slick when it was first discovered by the Coast Guard?

Question