Three consecutive traffic signals each show either red or green. How many different arrangements of the three signals are possible? (Note: “Red-redgreen” is different from “green-red-red.”) Choose the correct choice from the following options:
A) 10 B) 9 C) 8 D) 7 E) 6
The best way to do this Q would be to find the ways separately for each type of arrangements..   all three of same colour= 1*2(for green and red)= 2..   two of one colour and third different colour= 3!/2!=3..   total= 1*2+3*2= 
<gadget id="calculator">1*2+3*2</gadget>
<output>8</output>
8   ANSWER:8
<result>C</result>
Three consecutive traffic signals each show either red or green. How many different arrangements of the three signals are possible? (Note: “Red-redgreen” is different from “green-red-red.”)