Extension: LCM 3 Three lights, red, yellow and green, are controlled by switches. At the start, the three lights are switched on simultaneously. The red light stays on for 2 seconds, then is switched off for 2 seconds, and the pattern repeats. The yellow light is on for 4 seconds, off for 4 seconds. The green light is on for 3 seconds, off for 3 seconds. The three lights are switched on and off in their respective patterns for 15 minutes. Determine the total time, in minutes and seconds, that exactly two lights are on.