Adjusting an average after removing two values: The average of 50 numbers is 38. If two values, 45 and 55, are excluded, what is the average of the remaining 48 numbers?

Difficulty: Easy

Correct Answer: 37.5

Explanation:


Introduction / Context:
Average adjustments are often easiest by working with totals. Removing some values reduces both the total and the count; recompute the mean from the new total and count.


Given Data / Assumptions:

  • Initial count = 50; average = 38
  • Removing values 45 and 55


Concept / Approach:
Compute original total, subtract the removed numbers, then divide by the new count (48).


Step-by-Step Solution:
Original total = 50 * 38 = 1900New total = 1900 - (45 + 55) = 1900 - 100 = 1800New average = 1800 / 48 = 37.5


Verification / Alternative check:
Because 45 and 55 average to 50 (above 38), removing them should decrease the mean, which aligns with 37.5.


Why Other Options Are Wrong:
36.5 and 37 are too low; 37.52 is a rounding-like distractor; 38 ignores the removal of above-average values.


Common Pitfalls:
Dividing by 50 after removal or forgetting to subtract both removed values from the total.


Final Answer:
37.5

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