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prealgebra senior
Problem
Small lights are hung on a string inches apart in the order red, red, green, green, green, red, red, green, green, green, and so on continuing this pattern of red lights followed by green lights. How many feet separate the 3rd red light and the 21st red light? Note: foot is equal to inches.
(A)
(B)
(C)
(D)
(E)
Solution
We know the repeating section is made of red lights and green lights. The 3rd red light would appear in the 2nd section of this pattern, and the 21st red light would appear in the 11th section. There would then be a total of lights in between the 3rd and 21st red light, translating to -inch gaps. Since the question asks for the answer in feet, the answer is .
Final answer
E