Ranking test – same person counted from both ends: A line of girls is formed. One girl is 19th when counted from both the left end and the right end. How many girls are there in the line?

Introduction / Context:If a specific person's rank from both ends is known and it is the same person (not two different), the total equals the sum minus one—because the person is counted in both ranks.

Given Data / Assumptions:

• The same girl is 19th from left and 19th from right.
• No ties; single-file line.

Concept / Approach:Use N = left_rank + right_rank − 1 = 19 + 19 − 1.

Step-by-Step Solution:

Verification / Alternative check:There are 18 girls to her left and 18 to her right; adding her makes 37 total.

Why Other Options Are Wrong:38 or 39 double-count the middle girl; 27 is unrelated to the identity.

Common Pitfalls:Forgetting to subtract 1 when combining top/bottom ranks of the same person.

Final Answer:37