Question

Seven students, Q, R, S, T, W, X and Y, are sitting in a straight line facing north. Only W sits to the right of R. Only three people sit to the left of S. Only three people sit between R and Y. Q sits at some place to the left of T but at some place to the right of X. How many people sit to the left of X?

• A. Three
• B. One
• C. Two
• D. None

Answer 1

Answer:

D. None

No one (zero) sits to the left of X.

1. "Only W sits to the right of R": This places R in the 6th position and W in the 7th (last) position.

   • _ , _ , _ , _ , _ , R , W

2. "Only three people sit to the left of S": This means S must be in the 4th position.

   • _ , _ , _ , S , _ , R , W

3. "Only three people sit between R and Y": Counting three spots to the left of R (positions for S and two empty spots), Y must be in the 2nd position.

   • _ , Y , _ , S , _ , R , W

4. "Q sits at some place to the left of T but at some place to the right of X": The remaining three students must be arranged in the order of X ... Q ... T from left to right. Placing them into the three remaining vacant spots gives us:

   • X in the 1st position

   • Q in the 3rd position

   • T in the 5th position

Final Arrangement (Left to Right):

X → Y → Q → S → T → R → W

Since X is sitting at the extreme left end of the line, there are 0 people sitting to the left of X.