2,863 views
4 votes
4 votes

Lights of four colors (red, blue, green, yellow) are hung on a ladder. On every step of the ladder there are two lights. If one of the lights is red, the other light on that step will always be blue. If one of the lights on a step is green, the other light on that step will always be yellow. Which of the following statements is not necessarily correct? 

  1. The number of red lights is equal to the number of blue lights 
  2. The number of green lights is equal to the number of yellow lights 
  3. The sum of the red and green lights is equal to the sum of the yellow and blue lights 
  4. The sum of the red and blue lights is equal to the sum of the green and yellow lights

3 Answers

Best answer
7 votes
7 votes

Question says "On every step of ladder there are $2$ bulbs"

"If one is Green other must be Yellow". So one pair of lights possible = $\color{maroon} {(G,Y)}$

"If one is Red other must be Blue". Other pair possible = $\color{maroon} {(R,B)}$

So, from the above statements, we can conclude that there will be no pair as $(G,B)$ or $(G,R)$ or $(R,Y)$. But, the pair $\color{maroon} {(Y,B)}$ is a possible combination of lights in one of the ladder.

If we consider that there are $3$ steps in ladder as $(G,Y)$ , $(B,Y)$ and $(B,Y)$.

NONE OF THE ABOVE OPTION MATCHES (Official key was D though)

selected by
1 votes
1 votes
The answer should be D.
0 votes
0 votes
(D) is not necessarily true.

here red light= blue light

and green light= yellow light
Answer:

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