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Question 28933: Arithmetic Mean Retaining Multiplicities

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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R0056-28933 · q-20261005-advance-20261006-r07-descriptive-statistics-0008

Original question and givens

The nonempty observation list is D=[10, 0, 0, 0, -9, -9]. Retain every repetition. Find the arithmetic mean. Give a reduced fraction with positive denominator, retaining /1 for integers.

  • G001 — The nonempty observation list is D=[10, 0, 0, 0, -9, -9]. Retain every repetition. Find the arithmetic mean. Give a reduced fraction with positive denominator, retaining /1 for integers.

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

source roles = [qf-statistics-observation-mean, observation_mean]

After

derived = [exact_empirical_mean_fraction]

Conditions: none

Use the declared scalar/set/Yes-No/fraction answer role;integer fractions retain/1.Do not add an undeclared domain or change original bilingual data,formulas or questions.

Step identifiers and dependencies

Rule: R56_source_answer_role_and_EXACT_family_interface · Uses: G001

S002 · implies

Before

source roles = [[10, 0, 0, 0, -9, -9]]

After

derived = [[-9, -9, 0, 0, 0, 10], 6]

Conditions: none

Retain EVERY observation,including repeated values.Numeric sorting changes order only,not n or the sum;do not deduplicate as a set or sort lexically.These are sample summaries,not inferred population laws.

Step identifiers and dependencies

Rule: Statistics_FULL_observations_MULTIPLICITY_and_numeric_order · Uses: G001, S001

S003 · calculation

Before

Statistics ORIGINAL ALL observations sum := sum(10, 0, 0, 0, -9, -9)

After

Statistics ORIGINAL ALL observations sum = -8

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Statistics ORIGINAL observation sum over count := div(-8, 6)

After

Statistics ORIGINAL observation sum over count = -4/3

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · implies

Before

source roles = [[10, 0, 0, 0, -9, -9], -8, 6]

After

derived = [-4/3]

Conditions: none

The mean is the sum of EVERY observation divided by its count.Repetitions each contribute.It may be negative or unattained;reduce with positive denominator and retain/1.

Step identifiers and dependencies

Rule: Statistics_exact_empirical_mean_not_frequency_dedup_mean · Uses: G001, S004

Reverse checks

  • S005 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.
  • S004 · premise_and_result_audit — Recompute Statistics ORIGINAL observation sum over count with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Statistics ORIGINAL ALL observations sum with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.
  • S001 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.

Result

-4/3

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: 16968816e091ab48e00d48f522478ccbc09b7ab52c19e1b805ade3353d613020
  • candidate record SHA-256: f4135cdff9aa975d564391f3fbb490d10cf6117769adf893342b32300a340c7a
  • semantic review receipt SHA-256: 8bbda4edbed7078634ae88342998c79bcfb95de96187fac119c3b08e0adb0bc8
  • question-first witness SHA-256: 3edafa72d63d16a22414892b55806430e0a25b15b926d04f312550179607759f
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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