The average of the sequence 100, 200, 300, ..., 1000 is 550. If each term is divided by 5, what is the new average?
Correct Answer: None of these
Introduction / Context:Transformations applied uniformly to every term in a data set apply the same transformation to the average. This property lets us compute new averages quickly without re-summing all terms.
Given Data / Assumptions:
- Original sequence: 100, 200, 300, ..., 1000 (step 100)
- Original average = 550
- Operation: divide each term by 5
Concept / Approach:If each data point is divided by a constant k, the average is also divided by k. Thus New average = Old average / 5.
Step-by-Step Solution:
Old average = 550 New average = 550 / 5 = 110Verification / Alternative check:New sequence becomes 20, 40, 60, ..., 200. The first and last terms’ mean is (20 + 200) / 2 = 110, matching the transformation rule.
Why Other Options Are Wrong:
- 450: Incorrect scaling; seems like subtracting 100 instead of dividing.
- 45 and 55: Both reflect order-of-magnitude mistakes.
- None of these: Correct, since the true new average 110 is not listed among the numeric options.
Common Pitfalls:Confusing division with subtraction, or mistakenly dividing by the number of terms again after transformation.
Final Answer:None of these (the correct new average is 110).