All tractors made by a company are produced on one of three assembly lines, named red, white, and blue. the chances that a tractor will start when it rolls off of a line are 94%, 90%, and 92% for lines red, white, and blue, respectively. 50% of the company’s tractors are made on the red line and 20% are made on the white line. what fraction of the company’s tractors do not start when they roll off of an assembly line?