National Day classroom with color lights, according to the rule of two yellow, two red and two green connecting line, the 27th light bulb is
This is a cyclical problem
According to the meaning of the title, six bulbs can be divided into a cycle
27÷6 = 4 …… three
It has been calculated that the 27th bulb is the third bulb after four cycles, that is, the third bulb in the cycle: yellow, yellow, red, green and green
The 27th bulb is a red bulb