The surface of a circular dart board has a small center circle called the bull's-eye and 20 pieshaped regions numbered from 1 to 20. Each of the pie shaped regions is further divided into three parts such that a person throwing a dart that lands on a specified number scores the value of the number, double the number, or triple the number, depending on which of the three parts the dart falls. If a person hits the bull's-eye with probability 0:01, hits a double with probability 0:10, hits a triple with probability 0:05, and misses the dart board with probability 0:02, what is the probability that seven throws will result in no bull's-eyes, no triples, a double twice, and a complete miss once?