G1.2 A signboard has red, yellow, and green flashing lights. The red, yellow, and green lights flash every 3 seconds, 4 seconds, and 8 seconds, respectively. At 0 seconds, the red, yellow, and green lights flash simultaneously. If at $Q$ seconds, the red and yellow lights flash together for the third time, find the value of $Q$.
There are 3 blinking lights, red, yellow, and green, on a panel. Red, yellow, and green lights blink every 3, 4, and 8 seconds, respectively. Suppose each light blinks at the time $t=0$. At time $Q$ (in seconds), there is the third time at which only red and yellow lights blink, determine the value of $Q$.
The L.C.M. of 3, 4, and 8 is 24. i.e. The lights blink patterns repeat every 24 seconds. If only red and yellow lights blink, but not the green light, then the first time it happens is $12 \mathrm{~s}$, the second time it happens is $12+24=36 \mathrm{~s}$, in the third time it happens is $36+24=60 \mathrm{~s}$. $Q=60$