Mean of close decimal values: Compute the average of 0.64204, 0.64203, 0.64202, and 0.64201.

Introduction / Context:
When numbers form a short arithmetic progression, the average equals the midpoint between first and last. This reduces calculation complexity and rounding errors.

Given Data / Assumptions:

• Numbers: 0.64204, 0.64203, 0.64202, 0.64201
• Count = 4

Concept / Approach:
Average of an AP = (first + last) / 2. Using endpoints avoids repeated decimal addition.

Step-by-Step Solution:

Verification / Alternative check:
Add all numbers directly: total = 2.56810. Divide by 4 gives 0.642025, same result.

Why Other Options Are Wrong:

• 0.64202, 0.64204, 0.642022, 0.642015: do not match the precise midpoint or full sum division.

Common Pitfalls:
Rounding too early or making carry mistakes when summing decimals. Using the midpoint is reliable here.

Final Answer:
0.642025