The integers from 1 through 25 are arbitrarily separated into five groups of 5 numbers each. The median of each group is identified. Let M equal the median of the five medians. What is the least possible value of M?
- A. 9
- B. 10
- C. 12
- D. 13
- E. 14
Work through 2026 AMC 8 Problem 22 on medians and optimization with a written solution, hints, and a visual explanation.
The integers from 1 through 25 are arbitrarily separated into five groups of 5 numbers each. The median of each group is identified. Let M equal the median of the five medians. What is the least possible value of M?
Answer: A · 9
In a group of 5, three numbers are ≤ its median. For M to be the median of the five medians, at least three groups must have median ≤ M. Those three groups contribute 3 × 3 = 9 distinct numbers that are ≤ M, so M ≥ 9.
3 × 3 = 9 ⇒ M ≥ 9Pair small numbers with the largest ones to keep three medians small: {1,2,3,24,25}, {4,5,6,22,23}, {7,8,9,20,21}, {10,11,12,13,14}, {15,16,17,18,19}. Exactly the 9 numbers 1–9 land in the three small-median groups.
The five medians are 3, 6, 9, 12, 17. Sorted, the middle one is 9, so M = 9 — matching the bound. The least possible value is 9.
median(3, 6, 9, 12, 17) = 9Loading practice tools…