Find the arithmetic mean of the six numbers: 13, 17, 25, 11, 26, and 10.

Introduction / Context:
The arithmetic mean is a fundamental measure of central tendency. Correctly summing values and dividing by the count provides the exact average.

Given Data / Assumptions:

• Values: 13, 17, 25, 11, 26, 10
• Number of terms = 6

Concept / Approach:
Average = total sum / number of terms. Keep addition accurate to avoid minor slips that can change the result.

Step-by-Step Solution:

Verification / Alternative check:
Add linearly: 13 + 17 = 30; +25 = 55; +11 = 66; +26 = 92; +10 = 102; 102 / 6 = 17. Matches paired-sums method.

Why Other Options Are Wrong:

• 20 and 25: Both exceed the maximum-limited mean for these values.
• 15: Below the computed mean; indicates an addition or division slip.
• None of these: An exact correct option exists (17).

Common Pitfalls:
Dropping a term or mis-adding one pair, which shifts the total and leads to a wrong average.

Final Answer:
17