Instructions [34 - 37 ]

Anirbid, Chandranath, Koushik, and Suranjan participated in a puzzle solving competition. The competition comprised 10 puzzles that had to be solved in the same sequence, i.e., a competitor got access to a puzzle as soon as they solved the previous puzzle. Some of the puzzles were visual puzzles and the others were number-based puzzles. The winner of the competition was the one who solved all puzzles in the least time. The following charts describe their progress in the competition. The chart on the left shows the number of puzzles solved by each competitor at a given time (in minutes) after the start of the competition. The chart on the right shows the number of visual puzzles solved by each competitor at a given time (in minutes) after the start of the competition.

Who had solved the largest number of puzzles by the 20-th minute from the start of the competition?

Correct Answer: Koushik

To determine who solved the largest number of puzzles by the 20-th minute from the start of the competition, we need to analyze the chart on the left, titled "All puzzles".

Let us first understand the representation of the chart:
1. Horizontal Axis (X-axis): Represents the elapsed time in minutes after the start of the competition. The major grid lines are marked at intervals of 10 minutes (0, 10, 20, 30, 40), with intermediate grid lines at intervals of 2 minutes (e.g., 2, 4, 6, 8, etc.).
2. Vertical Axis (Y-axis): Represents the total number of puzzles solved.
3. Color Coding for Competitors:
• Anirbid: Red line
• Chandranath: Yellow line
• Koushik: Green line
• Suranjan: Blue line

Now, we look at the vertical line corresponding to the 20-th minute (Time = 20 on the horizontal axis) and read the height (number of puzzles solved) for each competitor:
• Koushik (Green line): At the 20-th minute, the green step function is at a height of 7. (He solved his 7-th puzzle at the 18-th minute and remained at 7 until the 25-th minute).
• Anirbid (Red line): At the 20-th minute, the red step function is at a height of 5. (He solved his 5-th puzzle at the 17-th minute and remained at 5 until the 21-st minute).
• Chandranath (Yellow line): At the 20-th minute, the yellow step function is at a height of 5. (He solved his 5-th puzzle at the 19-th minute and remained at 5 until the 22-nd minute).
• Suranjan (Blue line): At the 20-th minute, the blue step function is at a height of 4. (He solved his 4-th puzzle at the 18-th minute and remained at 4 until the 21-st minute).

Comparing the number of puzzles solved by each competitor at the 20-th minute:
• Koushik: 7 puzzles
• Anirbid: 5 puzzles
• Chandranath: 5 puzzles
• Suranjan: 4 puzzles

Therefore, Koushik had solved the largest number of puzzles by the 20-th minute.