Difficulty: Easy
Correct Answer: 63
Explanation:
Introduction / Context:
This item gives two separate rows. For each, use the “sum minus 1” rule to find the individual row size, then add the two totals.
Given Data / Assumptions:
Concept / Approach:
For a single row: N = left + right − 1. Compute for both rows and add.
Step-by-Step Solution:
Verification / Alternative check:
Check each row via right = N − left + 1: For N1 = 30, right = 30 − 12 + 1 = 19; for N2 = 33, right = 33 − 14 + 1 = 20.
Why Other Options Are Wrong:
Common Pitfalls:
Confusing the two rows as one, or forgetting to subtract 1 for each.
Final Answer:
63
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