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

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