The plot below shows the relationship between the mortality risk of cardiovascular disease and the number of steps a person walks per day. Based on the data, which one of the following options is true?
A. The risk reduction on increasing the steps/day from 0 to 10000 is less than the risk reduction on increasing the steps/day from 10000 to 20000.
B. The risk reduction on increasing the steps/day from 0 to 2000 is less than the risk reduction on increasing the steps/day from 10000 to 20000.
C. For any 5000 increment in steps/day the largest risk reduction occurs on going from 0 to 5000.
D. For any 5000 increment in steps/day the largest risk reduction occurs on going from 15000 to 20000.
GATE 2024 · General Aptitude · Line Graph · medium
Answer: Option C is the true statement: for any 5000-step increment, the largest risk reduction occurs when going from 0 to 5000 steps/day, because the curve is steepest (most concave) at the low end.
Read the curve shape: The graph shows a strongly decreasing, concave curve. The steepest part is at very low step counts (0 to ~5000). Beyond 10000 steps the curve is nearly horizontal.
Evaluate Option A: The curve drops dramatically from 0 to 10000 steps (most of the total fall). From 10000 to 20000 it barely moves. So risk drop[0,10000] >> risk drop[10000,20000]. Option A claims the opposite — FALSE.
Evaluate Option B: Even the small 0 to 2000 segment at the steep part of the curve shows a visible drop. From 10000 to 20000 the curve is nearly flat. So risk_drop[0,2000] > risk_drop[10000,20000]. Option B claims the opposite — FALSE.
Evaluate Option C: The 5000-step intervals to compare are [0,5000], [5000,10000], [10000,15000], [15000,20000]. The curve is steepest in [0,5000], giving the largest vertical drop. Each subsequent interval has a smaller drop. Option C states the largest risk reduction for any 5000-step increment occurs at [0,5000] — TRUE.
Evaluate Option D: Option D claims the largest 5000-step risk reduction is from 15000 to 20000. This is the flattest part of the curve — the smallest, not the largest, reduction. Option D is FALSE.